diff --git a/datafusion/sql/src/unparser/dialect.rs b/datafusion/sql/src/unparser/dialect.rs
index fe278a0e1edc0..a3367dd96ce22 100644
--- a/datafusion/sql/src/unparser/dialect.rs
+++ b/datafusion/sql/src/unparser/dialect.rs
@@ -635,6 +635,18 @@ impl Dialect for BigQueryDialect {
     fn unnest_as_table_factor(&self) -> bool {
         true
     }
+
+    fn timestamp_with_tz_to_string(&self, dt: DateTime<Tz>, unit: TimeUnit) -> String {
+        // https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/data-types#timestamp_type
+        let format = match unit {
+            TimeUnit::Second => "%Y-%m-%d %H:%M:%S%:z",
+            TimeUnit::Millisecond => "%Y-%m-%d %H:%M:%S%.3f%:z",
+            TimeUnit::Microsecond => "%Y-%m-%d %H:%M:%S%.6f%:z",
+            TimeUnit::Nanosecond => "%Y-%m-%d %H:%M:%S%.9f%:z",
+        };
+
+        dt.format(format).to_string()
+    }
 }
 
 impl BigQueryDialect {
diff --git a/datafusion/sql/src/unparser/expr.rs b/datafusion/sql/src/unparser/expr.rs
index 54c8eeb1252d9..d34d0d980ebee 100644
--- a/datafusion/sql/src/unparser/expr.rs
+++ b/datafusion/sql/src/unparser/expr.rs
@@ -1860,8 +1860,9 @@ mod tests {
     use sqlparser::ast::ExactNumberInfo;
 
     use crate::unparser::dialect::{
-        CharacterLengthStyle, CustomDialect, CustomDialectBuilder, DateFieldExtractStyle,
-        DefaultDialect, Dialect, DuckDBDialect, PostgreSqlDialect, ScalarFnToSqlHandler,
+        BigQueryDialect, CharacterLengthStyle, CustomDialect, CustomDialectBuilder,
+        DateFieldExtractStyle, DefaultDialect, Dialect, DuckDBDialect, PostgreSqlDialect,
+        ScalarFnToSqlHandler,
     };
 
     use super::*;
@@ -3353,6 +3354,7 @@ mod tests {
             Arc::new(CustomDialectBuilder::new().build());
 
         let duckdb_dialect: Arc<dyn Dialect> = Arc::new(DuckDBDialect::new());
+        let bigquery_dialect: Arc<dyn Dialect> = Arc::new(BigQueryDialect::new());
 
         for (dialect, scalar, expected) in [
             (
@@ -3413,6 +3415,36 @@ mod tests {
                 ),
                 "CAST('2025-09-15 11:00:00.123456789+00:00' AS TIMESTAMP)",
             ),
+            // BigQuery: should be no space between timestamp and timezone
+            (
+                Arc::clone(&bigquery_dialect),
+                ScalarValue::TimestampSecond(Some(1757934000), Some("+00:00".into())),
+                "CAST('2025-09-15 11:00:00+00:00' AS TIMESTAMP)",
+            ),
+            (
+                Arc::clone(&bigquery_dialect),
+                ScalarValue::TimestampMillisecond(
+                    Some(1757934000123),
+                    Some("+01:00".into()),
+                ),
+                "CAST('2025-09-15 12:00:00.123+01:00' AS TIMESTAMP)",
+            ),
+            (
+                Arc::clone(&bigquery_dialect),
+                ScalarValue::TimestampMicrosecond(
+                    Some(1757934000123456),
+                    Some("-01:00".into()),
+                ),
+                "CAST('2025-09-15 10:00:00.123456-01:00' AS TIMESTAMP)",
+            ),
+            (
+                Arc::clone(&bigquery_dialect),
+                ScalarValue::TimestampNanosecond(
+                    Some(1757934000123456789),
+                    Some("+00:00".into()),
+                ),
+                "CAST('2025-09-15 11:00:00.123456789+00:00' AS TIMESTAMP)",
+            ),
         ] {
             let unparser = Unparser::new(dialect.as_ref());