The first edition of Life is to be published on 3 April. The supplement, which will come out every Thursday, has been produced in association with Nature, the science journal published on the same day.
Life will be co-branded, with Nature providing one page of science news.
Nature's sales team will offer advertising across both publications.
The move follows recent changes to the broadsheet, including the introduction of a daily Media Guardian page and a daily digest of the world's media.
Carolyn McCall, the managing director of Guardian Newspapers, said: "Our partnership with Nature offers an exciting opportunity for The Guardian to establish itself in a new commercial market. This is a pioneering relationship that will give advertisers the opportunity to maximise exposure across two influential platforms, making the new supplement a key element in our continuing investment in The Guardian."