Sebastian Lechner is the new chairman of the CDU in Lower Saxony.
According to party information, the 42-year-old received 88.5 percent of the delegate votes at a state party conference on Saturday in Braunschweig - there was no opposing candidate.
Lechner was elected for two years.
Immediately after the defeat in the state elections last fall, CDU top candidate Bernd Althusmann announced his withdrawal from the state presidency.
He led the national association for a little over six years.
In addition to Lechner, the entire state executive was to be re-elected at the party congress.
The CDU got 28.1 percent in the October 9 election - the party last got a lower value in a state election in Lower Saxony in the 1950s.
The SPD has governed with the Greens for almost two and a half months - the CDU had to go into opposition.
Lechner's candidacy was considered controversial in parts of the party, since his critics believed that as General Secretary he was partly responsible for the unsuccessful election campaign.
He sees the expansion of renewable energies and education policy as important issues in state politics.
Previously, he had already been chairman of the parliamentary group in the state parliament.