Wanyama attended Kamukunji High School, which fields a successful football team. Upon leaving High School, he also played with JMJ Academy for three years during which time he also joined Kenyan Premier League clubs Nairobi City Stars and AFC Leopards. In 2007, he joined Allsvenskan club Helsingborg but after the departure of his brother McDonald Mariga to Serie A side Parma in 2008, Wanyama returned to Kenya.
Wanyama made his debut for the Kenyan national team in May 2007, aged just 15 in a friendly against Nigeria. He also played in all six of Kenya's 2010 FIFA World Cup qualifiers. He became the captain of his national team in 2013. Represented the national team at the 2019 Africa Cup of Nations.