Some 95% of party delegates voted for Merz, already assured of leading the CDU after being backed by party members in December.
Germany's conservative Christian Democrats have chosen Friedrich Merz, a critic of former Chancellor Angela Merkel, as their new leader in the hope of reviving the party devastated by last year's general election defeat.
The 66-year-old from the CDU's traditional wing was elected by a huge majority among the 980 delegates who met by videolink on Saturday. Some 95% voted in favour of the only candidate, already assured of the job after being backed by party members in December.
Having failed in two previous attempts to secure the party leadership in recent years, Merz declared himself "profoundly moved" by the party's support.
After years of centrist politics under Merkel, Friedrich Merz favours a return to traditional conservatism for the CDU after the party suffered its lowest ever score in last September's election.
The humiliation prompted the defeated candidate for chancellor, Armin Laschet, to step down.
"We must be a strong opposition," vowed Merz, adding that the CDU was targeting victory in several regional elections this year.
After 16 years in power in Germany, the CDU is beginning a spell in opposition for the next four years. Olaf Scholz's newly formed government is made up of his social democrats backed by the greens and the liberal party.
The new conservative leader accused Scholz of inaction, citing the debate over compulsory vaccination against COVID-19 as well as the security crisis in Ukraine.
Without directly attacking the former chancellor, Merz made no secret of his wish to strike a clean break from the Merkel years.
Their rivalry dates back 20 years, when Angela Merkel, then CDU president, ditched Merz from the strategically important role of president of the party's parliamentary group.
In 2009 he withdrew from political life to focus on the world of finance. As a lawyer in a large Dusseldorf firm, he made his fortune and took on influential roles within large German companies, stepping down as a manager with Blackrock last year.
A Catholic and a married father-of-three, Merz also owns two planes, one of which he pilots himself.