The group, which has previously tried twice to get a foothold in the UK, will officially mark its return next month with the launch of a new restaurant in Reading.
This will be followed with the opening of sites in Oxford and Stratford.
It has also submitted plans to open a restaurant in Croydon.
A total of five sites are expected to launch before the end of the year.
Up to 400 Wendy's outlets could eventually open nationwide, creating 12,000 jobs in the process, with 30 to 50 employees per restaurant.
As well as restaurants, drive-thrus and grab-and-go locations, BigHospitality understands that Wendy's will also use dark kitchen sites to help grow its UK footprint, and has signed a delivery deal with UberEats.
Abigail Pringle, Wendy's chief development officer, said in media interviews over the weekend that with the UK burger and takeaway market growing the time was right for a return.
Wendy's return to the UK will also be used a springboard for growth in the rest of Europe.
In a statement, the group said: "The UK launch will spearhead a European-wide expansion as Wendy's looks to build on strong growth on the other side of the Atlantic, where the brand last year dethroned Burger King to become the No 2 player in the US hamburger market."
Founded in Ohio in 1969, Wendy’s has more than 6,700 outlets in 30 countries around the world.