Tergat shattered the world best marathon time by 43 seconds to win the Berlin race in a dramatic finish as he outsprinted Kenyan pacemaker Sammy Korir, who became an unexpected rival, to finish in 2 hours 4 minutes 55 seconds.
"Representing Kenya at next year's Olympics is my next stop and I'm looking at it as my last appearance for the country," he said after arriving to a hero's welcome from hundreds of fans, Sports Minister Najib Balala, and several MPs at Nairobi's main airport.
Tergat said he had been confident of setting a world record in Berlin after preparing for four months and felt upbeat and in control from the start of the race.
"I was disappointed by my second placing in last year's London marathon and set my heart on breaking the [world] record in Berlin," he said.
Balala said a street in Nairobi would be named after Tergat to mark his victory in Berlin.
The Kenyan's first win in six marathon starts gave him the third world record of his career, adding to his 10,000 metres track mark of 26:27.85, since broken by Ethiopia's Haile Gebrselassie, and his current 59:17 half-marathon world best.