Farah clocked 29:21 minutes for his fourth consecutive win in the event, finishing just ahead Japan’s Arata Fujiwara and Scott Overall, who will be part of Team GB’s marathon squad.
Although Farah’s time was not even close to his personal best of 27:44 mins, the 10,000 world silver medallist and 5,000m world champion claimed that was all part of the plan.
“It’s going well, it’s all going in the right direction,” he said.
“During the race, we (him and Fujiwara) stayed side by side. I kept in control and then decided to sprint with 200m to go. He is good, he is strong runner with a lot of running experience. But, you know, I am track runner so I have that speed at the end.
“I've had another year of running and I am feeling stronger now, compared to previous seasons.
“I am very excited about the Olympics, I just need to stay injury-free and focused. It’s all fine, it’s just nice to come back here and run in London."
Farah will now head back to his US training base in Oregon, where he'll continue to put in the heavy miles alongside influential coach Alberto Salazar.
He will look to upgrade his world silver in the 10,000m this summer but remains undecided about whether to compete again over half the distance just a few days later.
“I am going to give 110 percent in the 10,000m and see what happens,” he said.
Meanwhile, Great Britain's Mara Yamauchi claimed women's line honours in 32:52 mins, ahead of Welsh Caryl Mair Jones and Scot Freya Murray.
Around 10,000 people took part in the race, which started and finished in The Mall and followed a clockwise route around the City of Westminster and the City of London, including St Paul’s Cathedral, Millennium Bridge, Tate Gallery, London Eye, Big Ben and Houses of Parliament.