The elite women’s title landed in the hands of British distance runner Tish Jones, who grabbed an early lead and claimed a commanding victory.
Kachaga highlighted his superb form adding the world best time to the Paris Half Marathon title he won two months ago.
Shaving four seconds off compatriot Sammy Kitwara’s previous record of 33.31 set in San Francisco in May 2009 he ensured the global mark remained in Kenyan hands.
Gachaga had company from South Africa’s Elroy Gelant and Lesotho’s Namakoe Nkhasi with two kilometres to go before he made his move.
“The race was cool, it was against some really good athletes, I wanted to break the course record,” Gachaga said.
“I will now prepare for the Berlin Marathon which will be my first marathon but I will be back in Cape Town next year to defend my title.”
Nkhasi finished the race in second place in 33.27 with Gelant crossing the line third in 33.54.
“It was actually a good run for me, I had a bit of a downside in my athletics coming from Kenya and going into the South African season,” Galant said.
“I’m in the process of preparing my body, I broke down a lot of muscle just before SAs but it was a great, strong run for me.
“Over the last four kilometres when the Kenyan (Gachaga) pulled away with some surges I wasn’t able to go with them.”
At last year's race, South African 10km record-holder Stephen Mokoka posted a new national mark of 33.34 minutes.
Mokoka will next week line up in a 10 kilometre race in Manchester which is where he set a new South African best of 27.38 two years ago.
Cape Town-based Jones was in a class of her own as she won the elite women’s race from ticket to tape in a time of 39.50.
Jones recently finished 18th at the London Marathon shaving three minutes off her previous best (2:33.56).
“I just needed to see how I felt after the marathon, and I think running not that much slower but the 42km does help when you are running the 12km,” Jones said.
“It is a different race altogether, I can hear my breathing and I can hear sounds I don’t normally hear in marathon running.
“I couldn’t see the other girls behind me and I anticipated someone to overtake me but it never happened.”
She threw down the gauntlet three kilometres into the race opening a sizeable gap between her and Lebogang Phalula.
Nolene Conrad crossed the line in second place in 41.08 with Maria Shai third in 41.14.