The 53-year-old was promoted March 17, replacing Ralph Krueger after the Sabres lost 12 straight games and were 6-18-4. Granato was an assistant under Krueger.
Buffalo lost its first six games with Granato as coach (0-5-1) before going 9-11-2 in its final 22 games. The Sabres (15-34-7) were last in the NHL and did not qualify for the Stanley Cup Playoffs for a 10th straight season.
Granato said May 12 the Sabres gradually earned more respect from opponents and the players were energized and had a vision for the future. He also highlighted his ability to make adjustments within games and from game to game.
"There's definite signs of progress, I felt," Granato said. "I think that was obvious. Nobody here is satisfied, but you see and feel the confidence and belief system has changed."
General manager Kevyn Adams had said the Sabres would conduct a coaching search while considering Granato as a candidate.
"I just want to talk to a lot of different people with a lot of different backgrounds, so we're going to do that," Adams said in his postseason media conference. "And Donny totally understood.
"And I think he believes that he's ready and capable of being the head coach of this team, and I understand that he did a very good job under challenging circumstances, and now we'll go through the process."
The Sabres won the 2021 NHL Draft Lottery and have the No. 1 pick in the 2021 NHL Draft on July 23.
