The Blues have strengthened in several different positions, mainly in attack, with Thiago Silva and Ben Chilwell also joining in defence.
One of the areas that Frank Lampard was hoping to add in was the goalkeeper position, and the Blues have got their man.
Mendy has fans in Petr Cech and goalkeeping coach Christophe Lollichon, meaning that Chelsea supporters should have some faith in the goalkeeper.
However, with the 28-year-old coming into the squad, that means there could be some changes over the course of the campaign.
Moving Kepa Arrizabalaga on this summer was always going to be difficult.
The Blues paid £71.6million for the goalkeeper back in 2018, and the Spaniard still has five years left on his contract.
There was never a club who were going to sign him on a permanent transfer, with only the potential of a loan option on the cards.
However, Kepa has stuck with the team and is hoping to fight for his number one spot.
Last season was not his best, and twice throughout the season the 25-year-old was dropped for veteran Willy Caballero.
Lampard lost faith in the Spaniard and Mendy will offer real competition for his place in the upcoming campaign.
While Kepa is expected to start the season, the Senegalese international has the ability to overthrow his new teammate.
One of the big benefits to the new signing is his height, with Mendy being an imposing figure in the box and dealing with crosses.
It’s something which Kepa came under criticism for last season, with the Blues struggling from set pieces and from the wide areas.
The 2020/21 campaign is set to be a make or break one for Kepa.
If he continues to struggle and can’t fight off the challenge of new-man Mendy, then the Blues will almost certainly look to move him on either in January or next summer.
With the seven transfers that the Blues have made, it is clear that they are looking to make a statement and are aiming to get that Premier League title back.
If Kepa can’t show that he should be number one, then the club will move on from him.