Maimane’s meteoric rise led to him being elected as the DA's leader on May 10 2015. His election coincided with the resignation of former leader Helen Zille, after her eight-year tenure in the position.
Maimane praised his predecessor in his victory speech.
He was viewed as a young, sharp-toothed politician, who often pointedly criticised the ANC.
However, Maimane lost support within his party, as the DA failed to grow its support in May's national elections.
His resignation comes two days after former Johannesburg mayor Herman Mashaba vacated his position and three days after the announcement of Zille’s return to the party as federal council chair.
Former federal chairperson Athol Trollip announced his departure from the party, with Maimane.
Maimane has offered to remain with the DA, as parliamentary leader, until the end of the year.
Recent power shifts within the party could result in an uncertain future for the DA, as well as the nation's political balance.