His mother, Ethel Maimane, grew up in Cofimvaba in the Eastern Cape, and is of Xhosa ancestry in the Sidloyi clan.

In March 2011, his mayoral candidacy[10] was announced at the DA Election Manifesto Launch at Walter Sisulu Square in Soweto.

[14] On 31 July 2013, Maimane announced his intention to run for the DA nomination as a candidate for Premier of Gauteng[15] in the 2014 elections at Baliskis in Alexandra.

Two opponents joined the internal race: DA Gauteng Health spokesperson Jack Bloom and unknown outsider Vaughan Reineke.

[18] Ahead of the 2014 national elections, Mmusi appeared in a political advert titled "Ayisafani" which suggested that the ANC, under the leadership of Jacob Zuma, had fallen from grace.

The DA laid a complaint with the Independent Communications Authority of South Africa (ICASA), and a public hearing was held.

[19] While the DA grew its share of the vote in Gauteng in the 2014 election, the ANC retained control of the province with Maimane losing to David Makhura.

[20] Following this, Maimane opted against serving in the provincial legislature and was instead sworn in as a member of the National Assembly of South Africa.

Maimane was the only candidate for the post of Leader of the Opposition in the National Assembly and was elected unopposed, becoming the first black man to hold the position in South Africa's history.

[24] He was backed by prominent businessman Herman Mashaba[25][26] and on 10 May 2015, Maimane was elected leader of the DA at the party's 2015 federal congress in Port Elizabeth.

"[36] Later that month, the Federal Executive (Fedex) of the DA decided to expel Kohler Barnard from the party,[38] although the decision was subsequently reversed on appeal.

[39] Maimane argued that action against Kohler Barnard would have implications for perceptions of the DA amongst black voters, implying that political expediency may trump the merits of the case.

[42][43][44] In March 2017, former DA leader Helen Zille argued in a series of tweets that some elements of South Africa's colonial legacy made a positive contribution to the country.

[45] Zille subsequently apologised in light of the outrage generated, and Maimane referred the matter to a DA disciplinary process.

[47] Maimane later admitted in June 2018 to difficulties in his relationship with Zille, as a result of her continued role as Premier of the Western Cape after he became party leader.

[57] On 5 October 2017, Maimane and Johannesburg mayor Herman Mashaba led a march towards the Gupta family's South African home in Saxonwold against allegations of state capture.

[60] In September 2018, reports speculated that Maimane would run for the DA nomination as a candidate for Premier of the Western Cape in the 2019 elections.

[72] The DA underperformed and lost support in Gauteng, a province that the party was expected to gain control of through a coalition government.

[74] Despite the decline at national level and in some provinces, the party did manage to grow in the Free State, Northern Cape and KwaZulu-Natal, earning one seat more in each of the respective provincial legislatures.

[80] The following day, Herman Mashaba announced his intention to resign as Johannesburg mayor and DA member due to disputes with party leadership.

In his resignation speech, Maimane said "despite my best efforts, the DA is not the vehicle best suited to take forward the vision of building one South Africa for all."