be overjoyed at unexpected good news 喜出望外

“喜出望外”，汉语成语，指因遇到意外的喜事，心中非常高兴。可以翻译为“be overjoyed at unexpected good news，be delighted and surprised”等。

例句：

这次成功让他喜出望外。

He felt elated by the unexpected success.