It follows a competitive pitch process last month.
Consolidated PR linked its departure from the account to the agency's acquisition by Four Communications last year, and said it has other larger aviation client commitments in the UK. It represents Air France and Ireland-based CityJet.
PRWeek reported in May 2014 that Consolidated had been appointed to handle UK PR for Swiss in a three-year deal, as Switzerland’s national airline sought a "new direction" for comms across Europe with several different agencies hired for different countries. One of these, Achtung! of Germany, is now the lead agency.
Launch PR is to start work immediately on a UK brand and press office programme for Swiss, "focusing on the quality of the brand and its personal, attentive service".
A spokesperson for Swiss, part of the Lufthansa Group, said: "We can confirm the brief is similar to that set last year and that we are no longer working with previous UK incumbent."
Launch PR has secured the account on a retained basis.
Felix Rodel, Swiss International Air Lines director of UK and Ireland, said: "We’re really looking forward to our collaboration with Launch, having heard great things about it. Its strong focus on ideas and ambitious media execution were the reasons behind the appointment."
Launch PR founder and creative lead Johnny Pitt said: "Swiss is a brilliant airline and a great brand. Launch has a long history of working with progressive names in the travel sector and we’re looking forward to breaking into new media and social territories for it in the UK."
Consolidated had replaced Burson-Marsteller in the UK PR role.
Nick Clark, MD of Consolidated, said: "We’ve very much enjoyed working with the Swiss team in the UK. However, following our move to Four Communications we are no longer part of the independent network that owns this relationship and we have other larger aviation client commitments in the UK."
Swiss serves more than 106 destinations across the world from Zurich, Basel and Geneva.
This story was updated on 13 May with comment from Consolidated.