Hampshire will sign left-arm seamer Reece Topley from Essex on a two-year contract at the end of the season.
Topley, 21, made his England debut during the five-run victory over Australia on Monday, taking 1-35.
"I am delighted to be joining Hampshire, a club I have admired from a distance for some time," Topley told Hampshire's official website.
"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."
He has taken 125 wickets in first-class cricket at an average of 25.78 since making his debut in 2011.
