After High School, he played for JMJ Academy for three years and joined Kenyan Premier League clubs Nairobi City Stars and AFC Leopards.

[8] In 2007, he joined Allsvenskan club Helsingborg, but returned to Kenya in 2008 after his brother, McDonald Mariga, moved to Serie A side Parma.

[11] In the summer of 2010 Scottish Premier League club Celtic attempted to sign Wanyama but Beerschot did not allow him to leave.

[13] On 9 July 2011, Wanyama finally completed a £900,000 move to Celtic, after the Scottish club had failed to sign him the previous year.

Wanyama chose 67 as his squad number to honour the Lisbon Lions, Celtic's 1967 European Cup-winning team.

[29] Wanyama received a nomination for the PFA Scotland Young Player of the Year for 2012–13,[30] but the winner was announced as Leigh Griffiths[31] After much speculation and a previous breakdown in talks, on 11 July 2013, Wanyama signed for Premier League side Southampton for a fee claimed to be £12.5 million,[32] making him the first Kenyan to ever play in the Premier League.

I'm very grateful to be here and I'm looking forward to playing in the Premier League.He made his debut on 17 August 2013, in a 1–0 away win against West Bromwich Albion.

[36] He scored his first goal for the club in a 1–0 league victory over Swansea City at the Liberty Stadium on 20 September 2014, after replacing James Ward-Prowse in the 69th minute.

"[36] On 23 June 2016, Premier League club Tottenham Hotspur announced that they had reached an agreement with Southampton for the transfer of Wanyama,[40] signing a five-year contract for a fee of £11 million.

[42] Wanyama scored his first goal for the club on his home debut against Crystal Palace, in the 82nd minute of a 1–0 league win for Spurs.

[52] On 3 March 2020, Tottenham announced that it had agreed to transfer Wanyama to Major League Soccer club Montreal Impact (now CF Montréal), where he would become a Designated Player.

[53][54] On 11 March 2020, Wanyama made his competitive debut for Montreal at Stade Olympique in the first leg of a quarterfinal in the CONCACAF Champions League, where he was named in manager Thierry Henry's starting side.

[62] In September 2021, after being repeatedly overlooked for selection during the 2022 FIFA World Cup qualifiers, Wanyama announced his retirement from international football, marking the end of his 14-year duty.

[63] However, following the FKF's re-admission in global competitions by FIFA and a personal meeting with Kenya's Sports Minister at the time, Ababu Namwamba, in December 2022 the midfielder officially agreed to restore his eligibility for the senior national team, together with Michael Olunga.

In 2015, Wanyama participated in the production of a short film about football in Kenya called Mdudu Boy, written and directed by actress Ella Smith.