The "Feeling better than ever" campaign will run across digital and print. Ads will be placed in women's consumer magazines and national supplements, and a new website will go live in May.
The campaign, created by agency LEG, uses a 42-year-old model to appeal to women who are "young at heart" and "coping with a changing body shape".
Playtex said a number of "high-profile" celebrities will appear in the campaign to promote a rollout of new products throughout the year.
Marcia Carleschi, marketing manager at Playtex, said: "The aim of our marketing campaign is to reposition Playtex as the lingerie label for British women in their 50s.
"We've conducted extensive research over two years and we understand what these women want but are not getting from what's currently out there – they feel ignored. We're confident that Playtex's new approach, product and campaign will help plug a sizeable gap in the market and really drive our distribution."