During her time with the Wildcats, the 28-year-old made 157 appearances, scoring 23 times.
Prior to a spell with Sunderland, Mollie spent a year and a half with United, being named club captain for the 2016/17 season.
“It’s a huge club, a huge move, and I’m really looking forward to it. The club’s ambitions and goals, working under Tanya herself, the answers were all there. It is amazing to be part of it and I can’t wait to be involved in the journey ahead," Lambert said upon signing for Newcastle United Women.