According to NFL Media insider Ian Rapoport, Watkins's contract guarantees him $19.9m (£11.9m) over the next four years, with a signing-on bonus of $12.8m (£7.7m).
Watkins signed his deal after his first practice session with quarterback EJ Manuel, and he preferred to focus on the future of his role in the team rather than on the money or length of the contract when questioned by reporters.
He said: "It's a blessing, definitely. But now I've got to move forward and perform.
"The relationship between me and EJ is coming along, but it's a process. We've got to clean up a little bit but this offense will learn. There'll come a time where it clicks and he's throwing the right passes and I'm running the right routes.
"I just want to get used to the playbook, bond with the quarterback, adapt fast and make sure it becomes first nature to me."
The Bills traded picks during the 2014 NFL Draft in order to choose Watkins at number four overall.