diff --git a/mysql-test/main/mdev_39999.result b/mysql-test/main/mdev_39999.result
new file mode 100644
index 0000000000000..fb96322e39dc0
--- /dev/null
+++ b/mysql-test/main/mdev_39999.result
@@ -0,0 +1,45 @@
+#
+# MDEV-39999: JSON_SEARCH must quote keys containing special characters
+#
+SELECT JSON_SEARCH('{"a.b":"x"}', 'one', 'x') AS path;
+path
+"$.\"a.b\""
+SELECT JSON_SEARCH('{"a[0]":"x"}', 'one', 'x') AS path;
+path
+"$.\"a[0]\""
+SELECT JSON_SEARCH('{"normal":"x"}', 'one', 'x') AS path;
+path
+"$.normal"
+SELECT JSON_SEARCH('{"hello world":"x"}', 'one', 'x') AS path;
+path
+"$.\"hello world\""
+SELECT JSON_SEARCH('{"a*b":"x"}', 'one', 'x') AS path;
+path
+"$.\"a*b\""
+SELECT JSON_SEARCH('{"a\\"b":"x"}', 'one', 'x') AS path;
+path
+"$.\"a\\\"b\""
+SELECT JSON_SEARCH('{"a\\\\b":"x"}', 'one', 'x') AS path;
+path
+"$.\"a\\\\b\""
+SELECT JSON_SEARCH('{"1abc":"x"}', 'one', 'x') AS path;
+path
+"$.1abc"
+SELECT JSON_SEARCH('{"":"x"}', 'one', 'x') AS path;
+path
+"$.\"\""
+SELECT JSON_VALUE('{"":"x"}', JSON_UNQUOTE(JSON_SEARCH('{"":"x"}', 'one', 'x'))) AS val;
+val
+x
+SELECT JSON_SEARCH('{"a.b":"x", "c":"x", "d[0]":"x"}', 'all', 'x') AS paths;
+paths
+["$.\"a.b\"", "$.c", "$.\"d[0]\""]
+SELECT JSON_VALUE('{"a.b":"found"}', JSON_UNQUOTE(JSON_SEARCH('{"a.b":"found"}', 'one', 'found'))) AS val;
+val
+found
+SELECT JSON_VALUE('{"a\\\\b":"found"}', JSON_UNQUOTE(JSON_SEARCH('{"a\\\\b":"found"}', 'one', 'found'))) AS val;
+val
+found
+SELECT JSON_SEARCH('{"a.b":{"c[d]":"x"}}', 'one', 'x') AS path;
+path
+"$.\"a.b\".\"c[d]\""
diff --git a/mysql-test/main/mdev_39999.test b/mysql-test/main/mdev_39999.test
new file mode 100644
index 0000000000000..c534e3c3ec814
--- /dev/null
+++ b/mysql-test/main/mdev_39999.test
@@ -0,0 +1,48 @@
+#
+# MDEV-39999: JSON path quoting for keys with special characters
+#
+
+--echo #
+--echo # MDEV-39999: JSON_SEARCH must quote keys containing special characters
+--echo #
+
+# Dot in key
+SELECT JSON_SEARCH('{"a.b":"x"}', 'one', 'x') AS path;
+
+# Bracket in key
+SELECT JSON_SEARCH('{"a[0]":"x"}', 'one', 'x') AS path;
+
+# Normal key (no quoting needed)
+SELECT JSON_SEARCH('{"normal":"x"}', 'one', 'x') AS path;
+
+# Space in key
+SELECT JSON_SEARCH('{"hello world":"x"}', 'one', 'x') AS path;
+
+# Asterisk in key
+SELECT JSON_SEARCH('{"a*b":"x"}', 'one', 'x') AS path;
+
+# Embedded double-quote in key
+SELECT JSON_SEARCH('{"a\\"b":"x"}', 'one', 'x') AS path;
+
+# Backslash in key
+SELECT JSON_SEARCH('{"a\\\\b":"x"}', 'one', 'x') AS path;
+
+# Key starting with digit
+SELECT JSON_SEARCH('{"1abc":"x"}', 'one', 'x') AS path;
+
+# Empty key
+SELECT JSON_SEARCH('{"":"x"}', 'one', 'x') AS path;
+SELECT JSON_VALUE('{"":"x"}', JSON_UNQUOTE(JSON_SEARCH('{"":"x"}', 'one', 'x'))) AS val;
+
+# JSON_SEARCH with 'all' mode - multiple matches
+SELECT JSON_SEARCH('{"a.b":"x", "c":"x", "d[0]":"x"}', 'all', 'x') AS paths;
+
+# Roundtrip: path from JSON_SEARCH works with JSON_VALUE
+SELECT JSON_VALUE('{"a.b":"found"}', JSON_UNQUOTE(JSON_SEARCH('{"a.b":"found"}', 'one', 'found'))) AS val;
+
+# Roundtrip with backslash key
+SELECT JSON_VALUE('{"a\\\\b":"found"}', JSON_UNQUOTE(JSON_SEARCH('{"a\\\\b":"found"}', 'one', 'found'))) AS val;
+
+# Nested object with special keys
+SELECT JSON_SEARCH('{"a.b":{"c[d]":"x"}}', 'one', 'x') AS path;
+
diff --git a/mysql-test/suite/json/r/json_no_table.result b/mysql-test/suite/json/r/json_no_table.result
index 500c7baaac169..8b084ac4d0e19 100644
--- a/mysql-test/suite/json/r/json_no_table.result
+++ b/mysql-test/suite/json/r/json_no_table.result
@@ -2740,7 +2740,7 @@ JSON_SEARCH
 'food'
   )
 )
-$.one potato
+$."one potato"
 select json_type(case (null is null) when 1 then
 json_compact('null') else
 json_compact('[1,2,3]') end);
diff --git a/sql/item_jsonfunc.cc b/sql/item_jsonfunc.cc
index 74477fd506e0d..584d97d7b8967 100644
--- a/sql/item_jsonfunc.cc
+++ b/sql/item_jsonfunc.cc
@@ -4378,9 +4378,45 @@ static int append_json_path(String *str, const json_path_t *p)
   {
     if (c->type & JSON_PATH_KEY)
     {
-      if (str->append(".", 1) ||
-          append_simple(str, c->key, c->key_end-c->key))
+      const char *k= (const char *) c->key;
+      size_t k_len= c->key_end - c->key;
+      bool needs_quote= (k_len == 0);
+      for (size_t i= 0; i < k_len; i++)
+      {
+        if (k[i] == '.' || k[i] == '[' || k[i] == ']' ||
+            k[i] == '"' || k[i] == ' ' || k[i] == '*' || k[i] == '\\')
+        {
+          needs_quote= true;
+          break;
+        }
+      }
+      if (str->append(".", 1))
         return TRUE;
+      if (needs_quote)
+      {
+        if (str->append('\\') || str->append('"'))
+          return TRUE;
+        for (size_t i= 0; i < k_len; i++)
+        {
+          if (k[i] == '"' || k[i] == '\\')
+          {
+            if (str->append('\\') || str->append(k[i]))
+              return TRUE;
+          }
+          else
+          {
+            if (str->append(k[i]))
+              return TRUE;
+          }
+        }
+        if (str->append('\\') || str->append('"'))
+          return TRUE;
+      }
+      else
+      {
+        if (append_simple(str, c->key, k_len))
+          return TRUE;
+      }
     }
     else /*JSON_PATH_ARRAY*/
     {