The Belgian went on to star for Inter Milan last season and said: "I’m happy and blessed to be back at this wonderful club. It’s been a long journey for me: I came here as a kid who had a lot to learn, now I’m coming back with a lot of experience and more mature.
"The relationship I have with this club means so much to me, as you know. I have supported Chelsea as a kid and now to be back and try to help them win more titles is an amazing feeling."
So where does Lukaku fit in to the Chelsea pay league? You can see all the Chelsea players and their weekly salaries for the 2021-22 season, according to Spotrac, an online sports team and player contract website, in the photo gallery above.
To move on to the next image, click on the arrows, or if you're using a mobile device, simply swipe.
Who is the highest paid star at Chelsea?
Lukaku does indeed lead the way at Chelsea, with a weekly wage of £325,000, or £16.9m a year, according to spotrac.com. That puts him ahead of World Cup winner N'Golo Kante and German forward Timo Werner.
The top 10 highest paid Chelsea players in 2021-2022
1. Romelu Lukaku, £325,000 a week
2. N'Golo Kante, £290,000 a week
3. Timo Werner, £272,000 a week
4. Ben Chilwell, £190,000 a week
5. Kepa Arrizabalaga, £155,000 a week
6= Cesar Azpilicueta, £150,000 a week
6= Kai Havertz, £150,000 a week
6= Mateo Kovacic, £150,000 a week
6= Christian Pulisic £150,000 a week
10. Callum Hudson-Odoi, £120,000 a week