The pair, who played married couple Mel and Steve Owen in the BBC soap nearly 20 years ago, surprised fans after they posed for a selfie.
"Well that was all sorts of nostalgic larks... thank you @martinjkemp @romankemp for having me on #sundaybest and so good to meet @sara.pascoe too," wrote the actress. "@itv spin off #melandstevethedeadyears #1998to2002 #eastenders #theowens."
WATCH: Everything you need to know about EastEnders
Fans were overjoyed to see the former co-stars reunite, with one writing: "This picture makes me so happy. I would be over the moon if both Steve and Mel came back to rule the Square together." Another remarked: "I remember the two of you being the sexiest couple in soapland, the chemistry you had was magic."
Their characters, Mel and Steve, were involved in a number of high-profile storylines during their reign on EastEnders. Steve was the prime suspect in the iconic Who Shot Phil story and in the murder of former flame Saskia Duncan, while Mel was kidnapped by hardman Dan Sullivan.
Tamzin Outhwaite and Martin Kemp reunited this week
Steve was later killed in dramatic scenes back in 2002 following a car chase with enemy Phil Mitchell.
Since leaving the show, both Tamzin and Martin have enjoyed successful acting careers. Tamzin, who went on to have daughters Florence and Marnie with ex-husband Tom Ellis, has starred in shows such as Red Cap, Hotel Babylon and New Tricks. She enjoyed a year-long return to EastEnders after 15 years away back in January 2018.
The pair played on-screen love interests Mel and Steve Owen
Martin, meanwhile, is married to Pepsi & Shirlie's Shirlie Holliman, and dad to daughter Harley Moon and son Roman. The 59-year-old has appeared in Family, Hustle and Birds of a Feather, and has starred as himself in shows including Lip Sync Battle.
Make sure you never miss a story! Sign up to our newsletter to get all of our celebrity, royal and lifestyle news delivered directly to your inbox.