Jeptoo clocked two hours 20 minutes 15 seconds to win comfortably ahead of compatriot Edna Kiplagat, with Japan’s Yikiko Akaby a surprise third.
Olympic champion Tiki Gelana paid the price after a nasty fall, colliding with wheelchair racer Josh Cassidy after 15 kilometres as she cut inside to get to a drinks station.
Meanwhile, Kebede won the men’s race in two hours six minutes four seconds, his second victory in the event.
The 2010 winner chased down Emmanuel Mutai and overtook the Kenyan in the closing stages to cross the line first.
GB ace Mo Farah remained true to his word and dropped out just before the halfway mark.
The double Olympic champion crossed Tower Bridge in the leading group, which reached 20 kilometres in 58 minutes 28 seconds, before slowing and stepping off the course.
GB’s David Weir, a six time winner, finished fifth in the men’s wheelchair race behind Australian winner Kurt Fearnley, while American Tatyana McFadden added the women’s wheelchair title to her victory in Boston earlier this week.
The victims of the bombings in America were remembered in a silent tribute before the start in London.