The actress and comedian, 63, has appeared on the chat show host’s programme since 2011 and is known for co-presenting the Grill Graham agony aunt segment.
She has also filled in for Norton, 57, as presenter on a number of occasions and together they have welcomed guests including Kylie Minogue, JK Rowling, David Tennant and Tina Turner.
She said: “Delighted to be joining Graham Norton on his new weekend shows and looking forward to tackling all the problems that Virgin Radio listeners decide to throw at us.”
Norton said: “Maria is amazing and the show just wouldn’t be complete without her. We’ll be there with all the best celebrity chat and all our usual antics broadcasting from our brilliant new home at Virgin Radio.”
— Virgin Radio UK (@VirginRadioUK) December 21, 2020
The pair worked together on ITV quiz show Carnal Knowledge, which featured two couples being asked personal questions about their sex lives. It aired in 1996.
Norton is joining Virgin Radio as a weekend host next year, following in the footsteps of ex-Radio 2 DJ Chris Evans.
Norton joined Radio 2 in 2010 to host the 10am to 1pm slot on Saturdays, taking over from Jonathan Ross
Strictly Come Dancing co-host Claudia Winkleman is set to replace him on the Saturday morning show. She will take over the slot from February.