Democratic Alliance (DA) spokesperson Lindiwe Mazibuko was on Thursday elected as the party's leader in Parliament.

She defeated incumbent Athol Trollip for the post.

Mazibuko, 31, was expected to win the contest after a number of party stalwarts, including leader Helen Zille, voiced their support for her.

She was elected by the DA's 83-member caucus. Zille also had a vote in the election. No voting percentages were immediately released by the party.

In a statement later, Mazibuko said she was honoured to accept the position of parliamentary leader of the DA.

"I thank my colleagues in the parliamentary caucus for endorsing my candidacy and pledge to serve and lead them to the best of my ability as we work towards our objectives," she said.

Mazibuko also paid tribute to Trollip.

He had served the caucus with distinction over the past two-and-a-half years and had accepted the outcome of the election with grace and aplomb, she said.

In the other mid-term caucus elections on Thursday, Elza van Lingen was elected DA leader in the National Council of Provinces, Wilmot James caucus chairperson, Marti Wenger deputy caucus chairperson, and Sandy Kalyan deputy chief whip.

Mazibuko named Watty Watson for the position of chief whip.

The elected whips are Stuart Farrow, Dion George, Patricia Kopane, Erik Marais, David Maynier, Gareth Morgan, Piet Pretorius, and Mike Waters.