diff --git a/.gitmodules b/.gitmodules
index 7510d1a707b74..f6ffb4fc35c4a 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -29,3 +29,6 @@
 [submodule "pglite/other_extensions/pgmq"]
 	path = pglite/other_extensions/pgmq
 	url = https://github.com/pgmq/pgmq
+[submodule "pglite/other_extensions/pg_bigm"]
+	path = pglite/other_extensions/pg_bigm
+	url = https://github.com/pgbigm/pg_bigm.git
diff --git a/pglite/other_extensions/Makefile b/pglite/other_extensions/Makefile
index 601f0ffb12545..d756fe86d3bcf 100644
--- a/pglite/other_extensions/Makefile
+++ b/pglite/other_extensions/Makefile
@@ -9,7 +9,14 @@ SUBDIRS = \
 		pg_uuidv7 \
 		pg_hashids \
 		pg_textsearch \
-		pgmq/pgmq-extension
+		pgmq/pgmq-extension \
+		pg_bigm
+
+# Every other extension here includes PGXS unconditionally. pg_bigm gates it
+# behind USE_PGXS and otherwise assumes it sits in the postgres tree as
+# contrib/pg_bigm, which resolves contrib-global.mk to a path that does not
+# exist from here. Set the flag for its build and its packaging step only.
+all-pg_bigm-recurse pg_bigm.tar.gz: export USE_PGXS = 1
 
 prefix ?= /pglite
 EXTENSIONS_BUILD_ROOT := /tmp/extensions/build
diff --git a/pglite/other_extensions/pg_bigm b/pglite/other_extensions/pg_bigm
new file mode 160000
index 0000000000000..16034b29a13a6
--- /dev/null
+++ b/pglite/other_extensions/pg_bigm
@@ -0,0 +1 @@
+Subproject commit 16034b29a13a6ef0241731b153e1b8db36779961