diff --git a/src/Illuminate/Database/Eloquent/Casts/AsCollection.php b/src/Illuminate/Database/Eloquent/Casts/AsCollection.php
index c2d567b504f7..7e65e9998a4b 100644
--- a/src/Illuminate/Database/Eloquent/Casts/AsCollection.php
+++ b/src/Illuminate/Database/Eloquent/Casts/AsCollection.php
@@ -19,11 +19,15 @@ public static function castUsing(array $arguments)
         return new class implements CastsAttributes {
             public function get($model, $key, $value, $attributes)
             {
-                return isset($attributes[$key]) ? new Collection(json_decode($attributes[$key], true)) : null;
+                return new Collection(isset($attributes[$key]) ? json_decode($attributes[$key], true) : []);
             }
 
             public function set($model, $key, $value, $attributes)
             {
+                if (is_null($value) || ($value instanceof Collection && $value->isEmpty())) {
+                    return [$key => null];
+                }
+
                 return [$key => json_encode($value)];
             }
         };