diff --git a/macros/edr/data_monitoring/data_monitors_configuration/get_column_monitors.sql b/macros/edr/data_monitoring/data_monitors_configuration/get_column_monitors.sql
index c32dcf520..ed5efe49f 100644
--- a/macros/edr/data_monitoring/data_monitors_configuration/get_column_monitors.sql
+++ b/macros/edr/data_monitoring/data_monitors_configuration/get_column_monitors.sql
@@ -1,13 +1,35 @@
 {% macro get_column_obj_and_monitors(model_relation, column_name, monitors=none) %}
 
-    {% set column_obj_and_monitors = [] %}
     {% set column_objects = adapter.get_columns_in_relation(model_relation) %}
+
+    {% if target.type == 'bigquery' %}
+        {% set expanded = [] %}
+        {% for col in column_objects %}
+            {% do expanded.append(col) %}
+            {% if col.fields | length > 0 %}
+                {# `BigQueryColumn.flatten()` discards ancestor modes, so a
+                   NULLABLE leaf under a REPEATED ancestor still satisfies
+                   `leaf.mode != 'REPEATED'`. Build the set of safe leaf names
+                   via an ancestor-aware walker and filter `flatten()` against
+                   it. #}
+                {% set safe_names = elementary.bq_safe_leaf_names(col) %}
+                {% for leaf in col.flatten() %}
+                    {% if leaf.name in safe_names %}
+                        {% do expanded.append(leaf) %}
+                    {% endif %}
+                {% endfor %}
+            {% endif %}
+        {% endfor %}
+        {% set column_objects = expanded %}
+    {% endif %}
+
     {% for column_obj in column_objects %}
         {% if column_obj.name.strip('"') | lower == column_name.strip('"') | lower %}
+            {% set wrapped = elementary.wrap_column_for_struct_support(column_obj) %}
             {% set column_monitors = elementary.column_monitors_by_type(
-                elementary.get_column_data_type(column_obj), monitors
+                elementary.get_column_data_type(wrapped), monitors
             ) %}
-            {% set column_item = {"column": column_obj, "monitors": column_monitors} %}
+            {% set column_item = {"column": wrapped, "monitors": column_monitors} %}
             {{ return(column_item) }}
         {% endif %}
     {% endfor %}
@@ -22,10 +44,11 @@
     {% set column_objects = adapter.get_columns_in_relation(model_relation) %}
 
     {% for column_obj in column_objects %}
+        {% set wrapped = elementary.wrap_column_for_struct_support(column_obj) %}
         {% set column_monitors = elementary.column_monitors_by_type(
-            elementary.get_column_data_type(column_obj), monitors
+            elementary.get_column_data_type(wrapped), monitors
         ) %}
-        {% set column_item = {"column": column_obj, "monitors": column_monitors} %}
+        {% set column_item = {"column": wrapped, "monitors": column_monitors} %}
         {% do column_obj_and_monitors.append(column_item) %}
     {% endfor %}
 
diff --git a/macros/edr/data_monitoring/monitors_query/column_monitoring_query.sql b/macros/edr/data_monitoring/monitors_query/column_monitoring_query.sql
index ecd1d3564..acc4fa7f8 100644
--- a/macros/edr/data_monitoring/monitors_query/column_monitoring_query.sql
+++ b/macros/edr/data_monitoring/monitors_query/column_monitoring_query.sql
@@ -15,7 +15,13 @@
     {%- set timestamp_column = metric_properties.timestamp_column %}
     {% set prefixed_dimensions = [] %}
     {% for dimension_column in dimensions %}
-        {% do prefixed_dimensions.append("dimension_" ~ dimension_column) %}
+        {% if elementary.bq_is_nested_identifier(dimension_column) %}
+            {% do prefixed_dimensions.append(
+                "dimension_" ~ elementary.bq_safe_alias(dimension_column)
+            ) %}
+        {% else %}
+            {% do prefixed_dimensions.append("dimension_" ~ dimension_column) %}
+        {% endif %}
     {% endfor %}
 
     {% set metric_types = [] %}
@@ -53,7 +59,7 @@
             ),
             filtered_monitored_table as (
                 select
-                    {{ column_obj.quoted }},
+                    {{ column_obj.quoted }}{% if column_obj.is_nested %} as {{ adapter.quote(column_obj.safe_alias) }}{% endif %},
                     {%- if dimensions -%}
                         {{
                             elementary.select_dimensions_columns(
@@ -78,7 +84,7 @@
         {%- else %}
             filtered_monitored_table as (
                 select
-                    {{ column_obj.quoted }},
+                    {{ column_obj.quoted }}{% if column_obj.is_nested %} as {{ adapter.quote(column_obj.safe_alias) }}{% endif %},
                     {%- if dimensions -%}
                         {{
                             elementary.select_dimensions_columns(
@@ -94,7 +100,7 @@
         column_metrics as (
 
             {%- if column_metrics %}
-                {%- set column = column_obj.quoted -%}
+                {%- set column = adapter.quote(column_obj.safe_alias) if column_obj.is_nested else column_obj.quoted -%}
                 select
                     {%- if timestamp_column %}
                         edr_bucket_start as bucket_start, edr_bucket_end as bucket_end,
@@ -341,17 +347,135 @@
     {% endif %}
 {% endmacro %}
 
+{# Segment-quotes nested dimensions on BigQuery and sanitises the alias suffix.
+   Backward compatible for non-nested columns and non-BQ adapters. #}
 {% macro select_dimensions_columns(dimension_columns, as_prefix="") %}
     {% set select_statements %}
     {%- for column in dimension_columns -%}
-      {{ column }}
       {%- if as_prefix -%}
-        {{ " as " ~ as_prefix ~ "_" ~ column }}
-      {%- endif -%}
-      {%- if not loop.last -%}
-        {{ ", " }}
+        {%- set _is_nested_bq = elementary.bq_is_nested_identifier(column) -%}
+        {%- set _source = elementary.bq_segment_quote(column) if _is_nested_bq else column -%}
+        {%- set _alias_suffix = elementary.bq_safe_alias(column) if _is_nested_bq else column -%}
+        {{ _source }}{{ " as " ~ as_prefix ~ "_" ~ _alias_suffix }}
+      {%- else -%}
+        {{ column }}
       {%- endif -%}
+      {%- if not loop.last -%}{{ ", " }}{%- endif -%}
     {%- endfor -%}
     {% endset %}
     {{ return(select_statements) }}
 {% endmacro %}
+
+
+{# ---------------------------------------------------------------------- #}
+{# BigQuery STRUCT nested-field helpers.                                  #}
+{# ---------------------------------------------------------------------- #}
+
+{# True only on BigQuery and only when `name` is a plain dotted identifier path
+   (e.g. user.address.city) — i.e. an actual nested STRUCT reference. Returns
+   false for plain identifiers, SQL expressions (dimensions are documented as
+   accepting arbitrary expressions, which must pass through untouched) and
+   non-BigQuery adapters. #}
+{% macro bq_is_nested_identifier(name) %}
+    {%- if target.type != 'bigquery' or name is not string -%}
+        {{ return(false) }}
+    {%- endif -%}
+    {{ return(modules.re.match('^\\w+(\\.\\w+)+$', name) is not none) }}
+{% endmacro %}
+
+{# Segment-quote a nested identifier path for BigQuery:
+   user.address.city -> `user`.`address`.`city`.
+   Anything that is not a nested identifier path (plain identifiers, SQL
+   expressions, non-BigQuery adapters) is returned unchanged, preserving
+   existing behaviour at all callsites. #}
+{% macro bq_segment_quote(name) %}
+    {%- if elementary.bq_is_nested_identifier(name) -%}
+        {%- set parts = [] -%}
+        {%- for seg in name.split('.') -%}
+            {%- do parts.append('`' ~ seg ~ '`') -%}
+        {%- endfor -%}
+        {{ parts | join('.') }}
+    {%- else -%}
+        {{ name }}
+    {%- endif -%}
+{% endmacro %}
+
+{# Convert a (possibly dotted) identifier into a dot-free alias safe to use
+   as a SQL identifier. No-op for names without dots. #}
+{% macro bq_safe_alias(name) %}
+    {{- name | replace('.', '__') -}}
+{% endmacro %}
+
+{# Wrap a Column / BigQueryColumn with a dict carrying the SQL identifier
+   representation (.quoted, segment-quoted for nested), a CTE-projection-safe
+   alias (.safe_alias, dot-free) and an .is_nested flag. For non-nested columns
+   and non-BigQuery adapters the wrapper mirrors the original Column's values
+   (safe_alias falls back to .quoted so identifier quoting is never lost), so
+   downstream consumers see no behavioural difference. #}
+{% macro wrap_column_for_struct_support(column_obj) %}
+    {%- set name = column_obj.name -%}
+    {%- set is_nested = elementary.bq_is_nested_identifier(name) -%}
+    {%- if is_nested -%}
+        {%- set quoted_segments = [] -%}
+        {%- for seg in name.split('.') -%}
+            {%- do quoted_segments.append('`' ~ seg ~ '`') -%}
+        {%- endfor -%}
+        {%- set quoted = quoted_segments | join('.') -%}
+        {%- set safe_alias = name | replace('.', '__') -%}
+    {%- else -%}
+        {%- set quoted = column_obj.quoted -%}
+        {%- set safe_alias = column_obj.quoted -%}
+    {%- endif -%}
+    {# `fields` only exists on BigQueryColumn; guard so non-BigQuery
+       adapters (Snowflake, Postgres, Redshift, ...) don't trip on the
+       attribute access. #}
+    {%- set fields = column_obj.fields if column_obj.fields is defined else [] -%}
+    {{ return({
+        'name': name,
+        'column': column_obj.column,
+        'quoted': quoted,
+        'safe_alias': safe_alias,
+        'is_nested': is_nested,
+        'dtype': column_obj.dtype,
+        'data_type': column_obj.data_type,
+        'fields': fields,
+    }) }}
+{% endmacro %}
+
+{# Walk a BigQuery STRUCT tree and collect dotted leaf names that are safe to
+   monitor without UNNEST — i.e. no REPEATED ancestor anywhere in the path,
+   and the leaf itself is not REPEATED. `BigQueryColumn.flatten()` returns leaf
+   columns with the leaf's own mode but discards ancestor modes, so this walker
+   is the source of truth for "which leaves can we project directly?". #}
+{% macro bq_safe_leaf_names(column_obj) %}
+    {%- set safe_names = [] -%}
+    {%- if column_obj.mode != 'REPEATED'
+            and column_obj.fields is defined
+            and column_obj.fields | length > 0 -%}
+        {%- for child in column_obj.fields -%}
+            {%- do elementary._bq_walk_collect(
+                child, [column_obj.column], false, safe_names
+            ) -%}
+        {%- endfor -%}
+    {%- endif -%}
+    {{ return(safe_names) }}
+{% endmacro %}
+
+{# Recursive helper: walks a google.cloud.bigquery.SchemaField subtree,
+   propagating whether any ancestor was REPEATED. Append safe leaf names to
+   `safe_names`. #}
+{% macro _bq_walk_collect(field, prefix, has_repeated_ancestor, safe_names) %}
+    {%- set new_prefix = prefix + [field.name] -%}
+    {%- if field.fields | length == 0 -%}
+        {%- if not has_repeated_ancestor and field.mode != 'REPEATED' -%}
+            {%- do safe_names.append(new_prefix | join('.')) -%}
+        {%- endif -%}
+    {%- else -%}
+        {%- set new_has_repeated = has_repeated_ancestor or (field.mode == 'REPEATED') -%}
+        {%- for child in field.fields -%}
+            {%- do elementary._bq_walk_collect(
+                child, new_prefix, new_has_repeated, safe_names
+            ) -%}
+        {%- endfor -%}
+    {%- endif -%}
+{% endmacro %}
diff --git a/macros/edr/data_monitoring/monitors_query/dimension_monitoring_query.sql b/macros/edr/data_monitoring/monitors_query/dimension_monitoring_query.sql
index 3aa20fe19..30119655a 100644
--- a/macros/edr/data_monitoring/monitors_query/dimension_monitoring_query.sql
+++ b/macros/edr/data_monitoring/monitors_query/dimension_monitoring_query.sql
@@ -12,8 +12,16 @@
         elementary.relation_to_full_name(monitored_table_relation)
     ) %}
     {% set dimensions_string = elementary.join_list(dimensions, "; ") %}
+
+    {# Segment-quote nested struct paths (e.g. user.address.city) for BigQuery so
+       they compile correctly. Plain identifiers, expressions and non-BigQuery
+       adapters pass through unchanged. #}
+    {% set sql_dimensions = [] %}
+    {% for dimension in dimensions %}
+        {% do sql_dimensions.append(elementary.bq_segment_quote(dimension)) %}
+    {% endfor %}
     {% set concat_dimensions_sql_expression = elementary.list_concat_with_separator(
-        dimensions, "; "
+        sql_dimensions, "; "
     ) %}
     {% set timestamp_column = metric_properties.timestamp_column %}
     {%- set data_monitoring_metrics_relation = elementary.get_elementary_relation(