Chepkok was born in Kapkitony in the Keiyo District of Kenya's Rift Valley Province. He won the silver medal in the junior race at the 2007 World Cross Country Championships, finished ninth at the 2009 World Championships and seventh at the 2009 World Athletics Final. He gained a major 5000 m win on the 2010 IAAF Diamond League circuit, winning at the British Grand Prix.
He came second at the Cross Internacional Zornotza behind Joseph Ebuya at the start of 2011. He gained a place on the senior Kenyan World team after coming third at the Kenyan National Cross Country Championships. He repeated that position at the 2011 IAAF World Cross Country Championships, securing the bronze medal behind Imane Merga and Paul Tanui, as well as sharing in the team gold with the Kenyan men. On the 2011 IAAF Diamond League circuit he was third at the Golden Gala, won at Athletissima, then came third at the Memorial van Damme final to place second overall in the 5000 m rankings.
At the start of the cross country season in November 2011, he came fourth at the Cross de Atapuerca but won the Cross de Soria a week later. He finished second to Edwin Soi at the Campaccio race, then finished behind Ebuya at the Cross Zornotza for a second year running. Chepkok was fifth at the 2012 African Cross Country Championships in March, taking the team title with Kenya. He was runner-up behind Sammy Kitwara at the World's Best 10K that month. He was fourth in the 5000 m at the Kenyan trials, missing a spot at the 2012 London Olympics, but ran a 10,000 metres best of 26:51.68 minutes at the Memorial Van Damme meet. He won the Cross Internacional de Venta de Baños in December.
His personal best times are 7:30.15 minutes in the 3000 metres, achieved in Doha in 2011; 12:51.45 minutes in the 5000 metres, also in Doha in 2010; and 28:23.46 minutes in the 10,000 metres, achieved in June 2006 in Barakaldo.
- Wokabi, James & Mutuota, Mutwiri (2011-03-04). Focus on Athletes - Vincent Chepkok. IAAF. Retrieved on 2011-11-21.
- Vincent Chepkok profile at IAAF
- Diego Sampaolo (2011-01-06). Ebuya and Kalovics take Campaccio Cross Country win. IAAF. Retrieved on 2011-01-15.
- Mutuota, Mutwiri (2011-02-19). Mutai and Masai take hard fought wins in Nairobi; reigning World champs Ebuya and Chebet won’t defend. IAAF. Retrieved on 2011-02-20.
- Minshull, Phil (2011-03-20). Merga gets a rare taste of victory – Men’s senior race report – Punta Umbrìa 2011. IAAF. Retrieved on 2011-03-29.
- 2011 Diamond League 5000 m final standings. IAAF. Retrieved on 2011-11-15.
- Valiente, Emeterio (2011-11-13). Merga and Masai confirm supremacy in Atapuerca as IAAF Cross Country Permit season kicks off. IAAF. Retrieved on 2011-11-15.
- Valiente, Emeterio (2011-11-20). Chepkok and Jeptoo unopposed at Soria. IAAF. Retrieved on 2011-11-20.
- Sampaolo, Diego (2012-01-06). Soi defends in a thriller, Cherono dominates at Campaccio XC. IAAF. Retrieved on 2012-01-06.
- Valiente, Emeterio (2012-01-09). Ebuya dominates in Amorebieta XC. IAAF. Retrieved on 2012-01-09.
- Williamson, Norrie (2012-03-19). Langat and Chepkirui take African XC titles in Cape Town. IAAF. Retrieved on 2012-03-25.
- Robinson, Javier Clavelo (2012-02-27). Kitwara and Cheruiyot run to triple crown in San Juan 10Km. IAAF. Retrieved on 2012-04-03.
- Valiente, Emeterio (2012-12-16). Chepkok and Cherono take the honours at Venta de Banos. IAAF. Retrieved on 2013-02-14.