Former Tshwane mayor and DA premier candidate in Gauteng, Solly Msimanga, was named the party's caucus leader in the Gauteng legislature on Friday.
Msimanga was elected to the position, beating former caucus and Gauteng leader John Moodey.
At a media briefing, held to announce his election, Msimanga said the party would do all it could to put pressure on the ANC.
The party went into the elections confident that it would push the ANC below 50% nationally and take Gauteng.
However, the party failed to meet its objectives and only managed to get 27%, which meant the party fell below its 2014 result of 30% in the province. The DA has 20 seats in the legislature.
At the media briefing at the Gauteng legislature, Msimanga said the ANC was leading by a very small majority in Gauteng and the legislature would be highly contested in the next five years.
"Under the stewardship of these elected leaders, the people of Gauteng can rest assured that their futures lie in capable hands," Msimanga said.
The caucus also elected Mike Moriarty as chief whip and Makashule Gana as caucus chair.
He added the party would ensure it maintains its election promise and come up with alternative solutions and policies that "speak to the people's needs".