The double Olympic champion signed off the season in style, bursting past Australia's Collis Birmingham to cross the finish line in a winning time of eight minutes and 40.04 seconds. Birmingham was eventually pipped to second place by Bobby Curtis.
A delighted Farah said: "I won't be thinking about any running in the next two weeks. I will go out for a couple of meals with my friends and family. It's important that I enjoy it and take a break and take my mind off running."
Farah added: "My lungs were on fire. Seriously, I was blowing for the first mile because it was pretty quick and I was thinking: 'I hope it's not going to carry on at this pace.'
"It slowly eased off, but I still had to work for it. It wasn't as easy as I thought. I've done a lot of stuff since becoming Olympic champion - I've had my two girls and done other stuff as well."
Elsewhere Farah's fellow Olympic gold medallist Greg Rutherford had to settle for second place in the men's long jump behind Great Britain team-mate Chris Tomlinson, who triumphed with a CityGames record leap of 8.18 metres.