Farah, who won gold in both the 5,000m and 10,000m at London 2012, won the two-mile race with ease.
The 29-year-old now has three reasons to celebrate after his wife Tania gave birth to twin girls on Friday.
"What a year I have had, it will never happen again. Two gold medals and two girls," said Farah.
"It was awesome," he added. "It hasn't been easy since the Olympics, with my daughters being born and everything that has been going on, but I want to thank everyone for all their help this year.
"I was a bit worried going into the race because I have not done much training because I have been doing a lot of running around, so to win was fantastic."
Tyson Gay, who was running the 200m for the first time in two years, finished second just behind Jamaican Nickel Ashmeade.
In the same race, British youngster Adam Gemili ran a personal best time of 20.53 seconds as he came in sixth place, ahead of fellow Briton Christian Malcolm.