The 50-year-old - who joined the BBC soap at the beginning of the year as pottery teacher Manda Best - will bow out of the show in the spring when her character discovers that boyfriend Minty Peterson (Cliff Parisi) is harbouring a "huge secret".
Of her decision to leave, the former Whose Line Is It Anyway? star told DS: "It has been an amazing year at EastEnders and I have made some fantastic friends among both the cast and crew."
She added: "I am somebody who likes to do a variety of different projects, and now seems the right time to move on."
Manda returned to Walford in March following the breakdown of her marriage and her son Adam's (David Proud) departure for university. Despite her teen romance with Phil Mitchell (Steve McFadden), Manda embarked on a relationship with his best friend Minty.
A Walford source commented: "Their relationship takes a turns for the worst when Manda discovers that Minty's been hiding something from her. The revelation then serves as the catalyst for Manda's exit."
Despite his screen mother's decision to quit, David Proud - EastEnders' first disabled adult character - will remain with the serial.
The source continued: "Even though Manda's leaving, Adam's sticking around in Walford. There's lots to come for him as the love triangle between Adam, Libby and Darren rumbles on."
Lawrence - who recently took part in Children In Need's Around The World In 80 Days challenge with Shane Ritchie - is due to finish filming next month but will remain on screen until early next year.
She will continue her hit run at The Comedy Store in Leicester Square, London.
At the end of last month, Barbara Windsor announced her decision to quit her role as Queen Vic landlady Peggy Mitchell after 15 years.
Almost a week later, the BBC confirmed that former Hollyoaks showrunner Bryan Kirkwood is to replace outgoing executive producer Diederick Santer when he steps down after the show's live anniversary episode.
On Friday, it was revealed that Bradley Branning actor Charlie Clements will also leave the programme in February.