"I want to thank the organisers and the wonderful crowd who made all the difference as we cycled by, helping to spur me on to finish the gruelling 100 miles in a respectable eight hours.
"Huge congratulations to everyone who took part
"RideLondon is now firmly on the map as one of the greatest cycling events in the world."
Mr Johnson, who battled with a puncture to complete the challenge in just over eight hours, was taking part in one of a number of events this weekend in what was billed as the UK's largest festival of cycling.
Mr Johnson said: "This is a great day for cycling, and for this city.
The Mayor of London managed to finish today's Ride London event in eight hours despite suffering a puncture.
Cyclists have begun racing across the capital as part of the Prudential RideLondon weekend, in one four separate events designed to appeal to riders of all ages and abilities.
Around 50,000 people are taking part in a mass event that saw many of the capital's roads closed to traffic yesterday.
London mayor Boris Johnson was among thousands of others taking part in a 100-mile road race today.
Well this is far from ideal.. In hospital with a broken collar bone. Thank you for all the messages. I will bounce back!
Thank you everyone for all your lovely messages. In pain this morning but doing ok and getting looked after :-)
Olympic gold medal winning cyclist Joanna Rowsell said she was "gutted" today after breaking her collar bone during a race as part of RideLondon, the UK's largest festival of cycling.
Rowsell, who won gold in the team pursuit during last year's Games, was competing in the women's criterium race in and around St James's Park last night when she was involved in a pile-up in the final stages of the event.
The Prudential RideLondon weekend features four separate events with around 50,000 people taking part in a mass participation event that saw many of the capital's roads closed to traffic yesterday, and London mayor Boris Johnson among thousands of others taking part in a 100-mile road race today.
Rugby World Cup winner Matt Dawson has tweeted a picture of himself alongside Olympic rowing star James Cracknell, saying "Here we go. There's no point competing with this fella."
Amazing a sport that starts earlier than rowing - cycling! My 'wave load' time for RideLondon is pre-crack of sparrow's fart at 05.58, hmm.
Heading over to Olympic Park for RideLondon. Streets strange mix of lycra clad warriors & people doing walk of shame home. I'd rather be...
Today more than 50,000 competitors will take part in a 100-mile road race on a route that starts in the Queen Elizabeth Olympic Park in east London, scene of last year's Games, before taking them into the Surrey countryside.
Rugby World Cup winner Matt Dawson, two-time Olympic rowing champion James Cracknell, former Olympic champion sprint hurdler Sally Gunnell and actor Gary Kemp are among the famous faces taking part.