"Marco Chiesa is the new SVP Party leader. Go Marco! Best of luck!" the party tweeted.
The SVP, a right-wing party and the largest in parliament, saw a decline in popularity under its outgoing leader, Albert Roesti, who announced his resignation last year.
The party is campaigning for capping immigration from the European Union. A motion to this effect will be put to a nationwide vote on 27 September under Switzerland's direct democracy.
If the Swiss vote to adopt the so-called Limitation Initiative the Alpine nation will be forced to terminate the deal on free movement as well as six other pacts it has with the EU, including on access to the EU market.