Major Phil Packer was greeted by hundreds of well-wisher lining the final mile of the course.
Reaching the finishing line is a personal triumph for the Royal Military Police Officer, who suffered catastrophic injuries during a rocket attack in Basra, Iraq, in February 2008.
“There were others who are coming back injured and my thoughts are really with their families at the moment,” he added.
The 36-year-old was told that he would never walk again after the attack in Basra, where he suffered a bruised heart, damage to his ribs and chest and the loss of the motor and sensory use of his legs.
But he battled the odds to take part in the marathon which started on April 26.
Maj Packer, who finished the race at about midday at St James's Park on the Mall, has raised £1 million for soldiers charity Help for Heroes.
He said: "Like the other thousands of fund-raisers who support Help for Heroes, I have reasons for feeling so passionate about his charity.
"While in hospital, I really needed something to pull me through some very dark and lonely days – Help for Heroes has done this and really helped me cope with what has happened."
Thanking the crowds who had gathered to meet him, he said he found it “very humbling because I am just a soldier and I’m not used to all this, really”.