She made her first international appearance in the junior race at the 2003 IAAF World Cross Country Championships, where she finished in fifth place and won the junior team silver medal along with Peninah Jepchumba. She competed at meetings in Spain and Portugal in 2004, running in the 1500 metres, 3000 metres and a couple of 10K runs. The following year she missed a place on the national team in cross country but she set a 3000 m best of 8:53.46 minutes at the Meeting Gaz de France in Paris. After taking second place at the Kenyan Athletics Championships, Chebet had her first senior podium finish at the 2006 African Championships, where she was the bronze medallist behind fellow Kenyans Edith Masai and Isabella Ochichi. In 2007, she did not finish in the heat of Mombasa at the 2007 IAAF World Cross Country Championships, but she won the 10,000 m. She finished ninth in the 10,000 m at the 2007 World Championships. In her final outing of the year she helped Kenya to second place at the Chiba Ekiden Relay, having run the 5 km leg.