diff --git a/dbt/adapters/sqlserver/sqlserver_helpers.py b/dbt/adapters/sqlserver/sqlserver_helpers.py
index 83d940a5..4d40cade 100644
--- a/dbt/adapters/sqlserver/sqlserver_helpers.py
+++ b/dbt/adapters/sqlserver/sqlserver_helpers.py
@@ -210,11 +210,17 @@ def build_server_arg(credentials: SQLServerCredentials) -> str:
 
 
 def format_connection_string_value(value: Optional[str], mssql_python_backend: bool) -> str:
-    """Format a connection-string value for the requested backend."""
+    """Format a connection-string value for the requested backend.
+
+    Inside a brace-quoted ODBC value a literal ``}`` must be doubled to ``}}``;
+    otherwise the driver treats it as the closing brace and misparses the rest
+    of the connection string.
+    """
 
     if mssql_python_backend:
         return escape_connection_string_value(value)
-    return "{" + ("" if value is None else value) + "}"
+    text = "" if value is None else str(value)
+    return "{" + text.replace("}", "}}") + "}"
 
 
 def format_pyodbc_driver_value(value: Optional[str]) -> str:
diff --git a/tests/unit/adapters/mssql/test_sqlserver_connection_manager.py b/tests/unit/adapters/mssql/test_sqlserver_connection_manager.py
index fb61e875..58fa2db2 100644
--- a/tests/unit/adapters/mssql/test_sqlserver_connection_manager.py
+++ b/tests/unit/adapters/mssql/test_sqlserver_connection_manager.py
@@ -38,6 +38,7 @@
 from dbt.adapters.sqlserver.sqlserver_helpers import (
     bool_to_connection_string_arg,
     escape_connection_string_value,
+    format_connection_string_value,
     is_mssql_python_backend,
     sanitize_connection_string_for_logging,
     validate_connection_requirements,
@@ -349,6 +350,18 @@ def test_escape_connection_string_value_quotes_only_when_needed() -> None:
     assert escape_connection_string_value("trailing ") == "{trailing }"
 
 
+def test_format_connection_string_value_doubles_braces_for_pyodbc() -> None:
+    assert format_connection_string_value("plain", mssql_python_backend=False) == "{plain}"
+    assert format_connection_string_value("pa}ss", mssql_python_backend=False) == "{pa}}ss}"
+    assert format_connection_string_value("}{", mssql_python_backend=False) == "{}}{}"
+    assert format_connection_string_value(None, mssql_python_backend=False) == "{}"
+
+
+def test_format_connection_string_value_delegates_for_mssql_python() -> None:
+    assert format_connection_string_value("plain", mssql_python_backend=True) == "plain"
+    assert format_connection_string_value("pa}ss", mssql_python_backend=True) == "{pa}}ss}"
+
+
 def test_sanitize_connection_string_for_logging_redacts_common_secret_fields() -> None:
     sanitized = sanitize_connection_string_for_logging(
         "SERVER=fake;UID=user@example.com;User Id=another@example.com;"