The ads use the line "Today doesn't have to be Pancake Day" along with a picture of two lemon halves. They were created by Publicis London.
The deal was brokered between Wonderbra's digital media agency Media Contacts and Lycos Network Europe, which manages advertising sales across .
The ads appear on the DeliaOnline homepage and in recipes for pancakes on the site; they lead through to Wonderbra's section of the Littlewoods Direct website.
Gordon Lee, marketing director at Wonderbra, said: "Research has shown that women who wear Wonderbras... have more fun than any other lingerie brand."
Sam Kayum, sales managing director for Lycos UK, said: "The fit with the DeliaOnline audience for this campaign was absolutely right for this work."
The creative is also running on out-of-home digital posters in five major cities, including Liverpool and Glasgow. The deal was brokered by Media Planning Group, with media owner Streetbroadcast.
Wonderbra recently ran a successful tactical campaign, with a viral spoof of the Cadbury's drumming gorilla ad with a Wonderbra-wearing model in the gorilla's place.