Kebede ran unopposed in the final 10 kms to clock two hours five minutes 19 seconds, nine seconds outside the course record set by Kenyan Olympic champion Sammy Wanjiru last year.
Chicago champion Liliya Shobukhova won the women's race in 2:22:00 on a cool damp morning.
During the buildup to the race Wanjiru said the Kenyans would run as a team in a bid to win a seventh consecutive men's title. Prophetically he also said Kebede, who finished second last year after a fierce battle over the final stages, was the opponent he feared most.
The men's field remained bunched until the halfway stage shortly after Tower Bridge, where Wanjiru, whose training had been hampered by a back injury, started to fade.
World champion Abel Kirui and the world silver medallist Emmanuel Mutai took up the Kenyan challenge but Kebede proved too strong, winning by 64 seconds ahead of Mutai. The admirably consistent Moroccan Jaouad Gharib, twice a world champion, finished third in 2:06:55.
Shobukhova, 32, one of a host of distinguished track runners who have graduated to the marathon, launched her challenge after the halfway mark.
Shobukhova, the European 5,000 metres record holder, always looked confident and strode comfortably over the closing kilometres to win by 19 seconds ahead of compatriot Inga Abitova with Ethiopian Aselefech Mergia in third place.
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