The contracts of the pair were allegedly up for renewal this summer, but the soap's producers took the decision to write them out in a storyline which sees their characters' relationship put to the test.
Speaking of the move, 25-year-old Tointon, who has played unlucky-in-love mother Dawn Swann since 2005, said: "Being at EastEnders has been the best four years of my life. The show has given me fantastic opportunities and I've been able to learn so much from the people I've worked with. I will always hold the show dear to my heart and will continue to be an avid fan."
She added: "I'm excited about what the next few months have in store for Dawn and as an actress I look forward to trying new roles."
Executive producer Diederick Santer said of the move: "EastEnders has benefited hugely from Ricky and Kara's great performances over the last few years. As individuals and together Garry and Dawn have had their share of comedy, drama and excitement and Ricky and Kara have delivered it all with talent, skill and flair."
He added: "They've got some fantastic stuff to come - this spring and summer sees their love truly put to the test - and they go with our thanks and very best wishes."
Meanwhile, an insider teased: "There's another spanner in the works to come for the hapless mechanic when his relationship with Dawn is once against tested this summer. Will there be a happy ending or will they go their separate ways when they leave Walford?"
The pair will remain filming until summer and will bow out on screen later in the year.