In Kenya, he played for Strathmore School, where he was also crowned Sportsman of the Year. He joined the Kenya Harlequins junior team. He was spotted by South African scouts at the 2006 Safari Sevens tournament, playing in the schools category for Strathmore School. In 2007, he joined to the academy. He progressed from Under–19 level in 2008 to Under–21 level in 2010.
Sharks
He was included in the squad for the 2010 Vodacom Cup, but failed to play in any matches. He did play in twelve Under–21 matches later in the year and was once again included in the squad for the 2011 Vodacom Cup competition, where he made his debut in the opening match of the season, a 30–19 victory over the. He made a total of ten appearances in that competition, scoring three tries. He was also included in the squad for the 2011 Currie Cup Premier Division, but failed to feature in that competition.
Blue Bulls
At the end of 2011, he was signed by the. He made eight appearances for them in the 2012 Vodacom Cup, but he was then released from his contract after just six months to join New Zealand ITM Cup team.
He joined prior to the 2012 ITM Cup. He made his debut against and played in eight matches for them on their way to winning the Championship and subsequent promotion to the Premiership. However, he wasn't named in their 2013 squad.
Kings
He joined the from Counties Manukau for the 2013 Super Rugby season. He was an unused substitute in the Kings' historic first ever match against the, but he did make his Super Rugby debut the following week, coming on as a late substitute against his former team the. He also appeared against the and then made his first Super Rugby start against the in Christchurch. However, after another substitute appearance against the, he fell below Rynier Bernardo in the pecking order and reverted to playing domestic rugby, playing three matches for the in the 2013 Vodacom Cup competition. One more substitute appearance in the home victory over the followed, as well as playing the opening match of the 2013 Currie Cup First Division season, but his season then came to a premature end following a torn bicep injury.
He also played for in the 2012 Varsity Cup, playing in three matches.
International
Internationally, he played for the Kenyan Under–18 and Under–21 national teams, and, although he initially expressed a desire to play for South Africa internationally, he declared himself available for for the 2015 Rugby World Cup qualifying series.
American football
On 25 July 2013, the NFL's Indianapolis Colts announced that they signed Adongo as an outside linebacker despite the fact that he had no prior American football experience. After spending time as a member of the Colts' practice squad, Adongo was added to the Colts' active roster on 3 December 2013. Adongo appeared in two games for the Colts in 2013, but did not record a tackle. On 7 August 2014, Adongo received a bicep injury during a pre-season game, and was waived with the injury designation by the Colts the following day. When he cleared waivers, he reverted to the Indianapolis Colts' injured reserve. On 5 September 2015, Adongo was waived by the Colts. He was signed to the practice squad the following day. Adongo was elevated to the active roster on 12 November. He was waived again on 17 December 2015 after law enforcement personnel received at least two reports of possible domestic violence between Adongo and an unidentified female.
