The 24-year-old had been heavily linked with a move to Liverpool, while the likes of Barcelona and Real Madrid had also been credited with an interest in his signature.
Chelsea have stolen a march on their rivals by triggering his £54m release clause, though, while Werner has reportedly agreed a five-year contract at Stamford Bridge.
Here, Sports Mole looks at which shirt numbers will be available to the Germany international in West London.
Werner's shirt number at Stamford Bridge could be relatively straightforward should he want to keep the current one he wears at RB Leipzig.
The 31-goal striker was given the '11' upon his arrival at the German outfit in 2016, and has enjoyed a prolific spell wearing that number on his back over the past four years.
The Chelsea '11' is currently taken, but its occupant Pedro will leave the club when his contract expires at the end of the season and his number will therefore become available.
Before becoming Leipzig's number 11, Werner wore number 19 for Stuttgart, although that shirt is occupied by Mason Mount at Chelsea and he is unlikely to surrender it unless he is promoted to a higher number.
The number nine is the most commonly associated with a star striker, but Tammy Abraham took that last summer and is not likely to be stripped of it following an impressive campaign.
The most notable numbers currently vacant at Chelsea are '6', '14' and '16', although none of those seems more suited to Werner than the 11.