Hampshire will sign left-arm seamer Reece Topley on a two-year contract from Essex at the end of this season.
The 21-year-old took 1-35 on his England debut in Monday's five-run Twenty20 victory over Australia.
Ipswich-born Topley took 36 wickets in 19 limited-overs matches for Essex this season, but was limited to just two appearances in the County Championship.
He has taken 125 wickets in first-class cricket at an average of 25.78 since making his debut in 2011.
"I am delighted to be joining Hampshire, a club I have admired from a distance for some time," Topley told the Hampshire website.
|BBC Essex's Glenn Speller: "It's a worry for Essex and their members that another bright, young prospect has decided his future lies elsewhere. Topley follows the recent examples of Adam Wheater, Ben Foakes and Tymal Mills in moving on from the county where he learnt his trade. The longer Essex remain in Division Two the more likely it is the talent drain will continue."|
"I know I am not the finished article and hope that, at 21 years old, Hampshire can help me develop into a regular international bowler in the coming years."
Hampshire director of cricket Giles White hopes the county can help Topley realise his ambitions both domestically and internationally.
"He's a young player with plenty of potential," he told BBC Radio Solent. "We're looking forward to working with him and obviously he has got a lot of ambition having played for the England T20 squad.
"He wants to play Test cricket, so hopefully we can help him realise his ambition as well as play a big part in our future over the years."