Helfrich, who was fired by Oregon after the 2016 season, will be part of the Bears' staff under new coach Matt Nagy.
After serving as offensive coordinator under Chip Kelly, Helfrich became head coach of the Ducks in 2013. He went 37-16 over four seasons, leading Oregon to the first College Football Playoff championship game after the 2014 season.
In those four seasons, Oregon averaged 42.6 points per game and 536.7 yards per game, which ranked second and third among FBS schools, respectively, during that time period.
Helfrich will try to right the ship, as the Bears are looking to become more offensive-minded under Nagy, who served as the offensive coordinator with the Chiefs prior to becoming the Bears' new head coach on Monday.
Nagy confirmed on Monday that he will be calling his own plays.
In addition, the Bears also hired Charles London as the team's running backs coach and Chris Tabor as special teams coordinator.
Since 2015, the Bears' offense is ranked tied for 30th in points per game (18.3).
The Bears finished 5-11 in 2017, haven't reached the playoffs since 2010 and have missed the postseason in 10 of the last 11 years. The Bears have finished last in the NFC North for four straight seasons.
Tabor spent the past seven seasons as Cleveland's special teams coordinator. The Browns ranked sixth in kickoff return average against (21.8), seventh in the NFL in punt return average (9.9), ninth in total kick return yards (8,974) and 10th in total return yards allowed (7,627) during that time. Tabor was Chicago's assistant special teams coach from 2008-2010.
London has spent nine seasons in the NFL -- the past four as Houston's running backs coach. He was an offensive assistant with the Bears from 2007-09.
ESPN's Jeff Dickerson contributed to this report.