While Buffalo made the playoffs for the first time since 1999 with a 9-7 record, it struggled mightily on offense throughout the season, ranking 29th in total yards per game (302.6) and 22nd in points per game (18.9).
The offense was also the greatest culprit in the Bills' AFC Wild Card playoff loss to the Jacksonville Jaguars, as they mustered just 263 yards in a 10-3 defeat.
The 59-year-old Dennison has extensive experience as an offensive coordinator. He served in that role with the Denver Broncos from 2006 through 2008 and with the Houston Texans from 2010 through 2013.
Dennison later returned to the Broncos to be their offensive coordinator from 2015 through 2016, winning Super Bowl 50 in that capacity.
He has also been a special teams coordinator and offensive line coach, and he was the Baltimore Ravens' quarterbacks coach in 2014.
Dennison had familiarity with Bills quarterback Tyrod Taylor from their time together in Baltimore, but the combination didn't prove fruitful in Buffalo.
Taylor went 8-6, threw just four interceptions and finished with 427 yards and four touchdowns on the ground, but he also threw for only 2,799 yards and 14 touchdowns.
Dennison's ouster also potentially increases the chances of Buffalo releasing or trading Taylor in favor of a new option at quarterback.
There are plenty of possibilities likely to be available via free agency or trade, plus the Bills own the No. 21 and 22 overall picks in the 2018 NFL draft.
In terms of potential replacements for Dennison, the Carolina Panthers recently fired offensive coordinator Mike Shula and quarterbacks coach Ken Dorsey.
Bills head coach Sean McDermott was previously a defensive coordinator in Carolina, while general manager Brandon Beane was part of the Panthers front office as well.