Emma Barton and Jamie Borthwick were both "struggling with nasty knee injuries" during the London Marathon but "refused to stop".
The "EastEnders" pair were part of the team Barbara's Revolutionaries, who took part in the event for their former co-star Dame Barbara Windsor - who was diagnosed with Alzheimer's disease in 2014 - and the 41-year-old star says Jamie was her "rock" over the 26.2 miles.
Emma - who plays Honey Mitchell in the BBC One soap - wrote on Twitter: "I did it... 6hrs26 mins... thank you to all who supported us on the day.. you really do carry us along. To those who donated.. this is what it was all about! @DementiaRev Thank you Jamie, my rock! We laughed,cried,struggled! Both nasty knee injuries..refused to stop though! (sic)"
Jamie (Jay Brown) says Emma acted as his "absolute rock" throughout the marathon, and has thanked the crowds for their support.
He wrote: "Wow wow wow !!! What a feeling crossing that line! This woman @theemmabarton was my absolute rock today! We did the whole marathon together!! What a day! The crowds are unbelievable so thank you to everyone who came, cheered and supported! And congratulations to every single person who ran the marathon this year! Particularly #Barbara'srevolutuonaries #londonmarathon (sic)"
The pair's co-star Natalie Cassidy (Sonia Fowler) also took part in the marathon as part of Barbara's Revolutionaries, and her heart "nearly exploded" when she saw co-stars Maisie Smith (Tiffany Butcher), Clair Norris (Bernie Taylor), and Danny Walters (Keanu Taylor) on the sidelines.
She wrote: "what can I say to you guys? My heart nearly exploded when I saw you. You will never realise how much that helps you when running. Thank you SO much. (sic)"
Clair tweeted: "We love you"
Barbara's Revolutionaries - which also featured Barbara's husband Scott Mitchell, and "EastEnders" stars Jake Wood (Max Branning), Adam Woodyatt (Ian Beale) and Tanya Franks (Rainie Branning), among others - ran for Dementia Revolution, a year-long charity of the year campaign from Alzheimer's Society and Alzheimer's Research UK.
They have raised more than £140,000 for the two charities, with the total standing at more than £163,000 including Gift Aid.