"他竟然赢了" 的英文表达方法有几种：

He actually won.

He surprisingly won.

He unexpectedly won.

He amazingly won.

He incredibly won.

其中，"actually"、"surprisingly"、"unexpectedly"、"amazingly" 和 "incredibly" 都是副词，表示"竟然"的意思，而 "won" 则是动词，表示"赢"的意思。

例句：

I can't bepeve he actually won the championship. (我真的不敢相信他竟然赢得了冠军。)

He surprisingly won the race despite the odds against him. (尽管他的胜算很小，他竟然赢得了比赛。)

No one expected him to win, but he unexpectedly took home the trophy. (没人想到他会获胜，但他竟然拿到了奖杯。)

She was amazed when he won the game in the final seconds. (当他在最后几秒赢得比赛时，她感到震惊。)

It was incredible that he managed to win the match with such a small lead. (他竟然在这样小的领先优势下赢得比赛，真是不可思议。)