The 29-year-old, who was a private chef from the Lake District, collapsed at the 22.5 mile mark and received immediate medical treatment, but later died in hospital.
Campbell reached the semi-finals of the 2017 series of MasterChef: The Professionals, where judge Marcus Wareing described his plate of cod cheeks, spirulina, kale and kombucha as the “best” signature dish he had ever eaten in the show.
He was running to raise money for The Brathay Trust – which inspires vulnerable young people to make positive changes in their lives - and in memory of his father Martin, who died in summer 2016.
Campbell’s family paid tribute to their “inspirational son and brother”, who had completed the Manchester Marathon in under three hours earlier this month.
Virgin Money, organisers of the London Marathon, said in a statement: “Everyone involved in the organisation of the London Marathon would like to express our sincere condolences to Matt’s family and friends.
“No further details will be released and the family has asked for privacy. The exact cause of death will be established by later medical examination.”
Campbell was aiming to raise £2,500 for The Brathay Trust, though his JustGiving page has now reached over £12,000.
To donate click here.