[2] Indongo debuted professionally at the age of 25, on 25 July 2009, with a points decision (PTS) win over Pohamba Mandume.
After improving to 14 consecutive wins, he won the WBO Africa light-welterweight title in October 2012 via victory over James Onyango.
[3] In October 2016, undefeated IBF and IBO light-welterweight champion Eduard Troyanovsky (25-0, 22 KOs) stated he would make a voluntary defence on the Lebedev-Gassiev card in Russia on 3 December.
[4] On 7 November, Indongo, who was ranked WBO #3, WBA #15 and IBF #10, was announced as his opponent, for the fight to take place in Moscow, in his first bout held outside of Namibia.
[5] Despite being a favoured underdog, Indongo knocked out Troyanovsky after only forty seconds of the first round with a left hook, becoming Namibia's fourth world boxing champion.
[6][7] In late December, there were talks for a potential fight between Indongo and WBA (Regular) Light Welterweight champion Ricky Burns.
[10][11] On 11 January, Sky Sports confirmed a deal was reached for Burns and Indongo title bout on 15 April 2017.
[16][17] On 1 July 2017, Top Rank announced that a light welterweight unification fight between Indongo and WBC, WBO, Ring magazine, and lineal champion Terence Crawford was agreed to take place on 19 August at the Pinnacle Bank Arena in Lincoln, Nebraska live on ESPN in US and Sky Sports in the UK.
[18][19][20] The projected unification of every major world title in boxing (WBA, WBC, IBF, WBO, The Ring, and lineal) will determine the light welterweight division's first undisputed champion since Kostya Tszyu in 2004, and the first time all the aforementioned titles have been at stake in a single fight since Bernard Hopkins vs. Jermain Taylor in 2005.
Tobias stated that Indongo was under contract with his MTC Nestor Sunshine Boxing & Fitness Academy until 2020.
[29] In January 2018, a deal was finally reached for the fight between Postol and Prograis to take place on 9 March at the Buffalo Run Casino in Miami, Florida.
[30] On 12 February, ESPN reported that Postol suffered a fractured thumb and forced to drop out of the bout.
In round two, Jones Johnson fought more aggressively, but a counter right hook from Indongo dropped him on the canvas.
Johnons managed to beat the count, but the referee decided he was not fit to continue, awarding Indongo with the TKO win.