Ainsworth, who had originally set himself the fundraising target of raising £30,000, chose to support the charity in honour of his father, whom he lost to the disease in 2015.
He completed the 26.2-mile course in five hours and 24 minutes.
“Having seen my father suffer from pancreatic cancer, I know the devastation it can cause to both the patient and family,” said Ainsworth.
“With it being one of the hardest cancers to identify, often it is too late to cure sufferers which is a heart-breaking reality for many.”
The money raised will be used to help develop detection tools and techniques that will identify pancreatic cancer at a stage where it can be treated and cured.
Describing the experience as one of the most incredible, brutal and emotional of his life, Ainsworth added: “I am broken, battered and bruised, but still smiling.”
Alongside No.6, Ainsworth also owns Padstow Townhouse and Rojano’s in the Square with his wife Emma.
Earlier this year it was announced they had taken on The Mariners pub in Rock, replacing their friend and fellow chef Nathan Outlaw.
Ainsworth’s sponsorship page is still open for donations, and can be found here.