McDonnell, 30, will face Rosas on the undercard of Anthony Joshua's IBF world heavyweight title bout with Charles Martin at the O2 in London.
It will be McDonnell's first fight in the UK since he defeated Argentina's Javier Chacon in Liverpool in 2014.
The Doncaster fighter, who has won 27 of his 30 fights, beat Japan's Tomoki Kameda in both of his past two bouts.
McDonnell won the WBA title with a 10th-round stoppage of Thailand's Tabtimdaeng Na Rachawat at Wembley Stadium in May 2014.
He had previously been stripped of the IBF title for failing to fight the federation's mandatory challenger in the advised timeframe.
"I cannot tell you how good it feels to be back fighting in the UK," said McDonnell. "It has been a long time coming.
"Rosas has won world titles. He has mixed it with the best and is very experienced.
"He will bring a lot to the table. He is only 31 so he will still be hungry. I hope we can put on a great fight and I am 100% confident I can beat him."
In other fights on the Joshua undercard, Lee Selby defends his IBF world featherweight title against Eric Hunter, three-time world super-middleweight title challenger George Groves faces unbeaten Scot David Brophy and Nigel Benn's son Conor makes his professional debut.
British WBA world bantamweight champion Jamie McDonnell will defend his title against Juan Alberto Rosas on 9 April.