Louise Blizzard,43, is believed to be only the second woman in history to hit that milestone.
The Warrington mum will be running in aid of the River Reeves Foundation which was set up after the death of local band Viola Beach.
Louise says she will keep running marathons until she is no longer able to: "If I do next years London Marathon, that should be a record for the most London Marathons run by a female.
"I plan to keep going a little bit longer if I can, each year it's quite over whelming being a part of it.
"It's just very very special."
Louise started running the London Marathon at the age of 18 and has done every year since apart from when she was pregnant with her son in 2010.
The Warrington mum grew up watching her dad run marathons and joined him for the first time in the capital at the age of 18 and her love of running blossomed from there. Louise has now passed on the athletic tradition to her son who also loves the sport.
Although Louise says it doesn't get any easier she hopes to compete the nearly 27 mile run in under 3 and a half hours: "I think it actually gets harder because I'm obviously getting older and I think every year a put pressure on myself to do well.
"So, I always try to run a good time and do the best I can on the day."
If you'd like to donate go to Louise's donation page.