The actress will take the reins of the NBC comedy sketch show on April 9, which will also feature the Foo Fighters as musical guests.
This will mark Mirren's first time hosting the show. She can next be seen alongside Russell Brand - who hosted earlier this month - in the comedy movie Arthur, which is released April 8 in the US and April 22 in the UK.
The network has additionally confirmed that Sir Elton John will host the April 2 show, where he will also appear as a musical guest alongside Leon Russell. It will mark his second time on the programme, after previously appearing back in 1982.
SNL airs Saturdays at 11.30/10.30c on NBC.