Cory Undlin is in his second season as the 49ers defensive passing game specialist/secondary coach. He joined the 49ers after spending the 2020 season as the defensive coordinator of the Detroit Lions.

Undlin and the 49ers defense ranked sixth in the NFL in 2021, allowing 206.5 passing yards per game. San Francisco saw eight different players record an interception on the season, as CB Emmanuel Moseley finished with a career-high 11 passes defensed and one interception.

Cory Undlin is in his second season as the 49ers defensive passing game specialist/secondary coach. He joined the 49ers after spending the 2020 season as the defensive coordinator of the Detroit Lions.

Undlin and the 49ers defense ranked sixth in the NFL in 2021, allowing 206.5 passing yards per game. San Francisco saw eight different players record an interception on the season, as CB Emmanuel Moseley finished with a career-high 11 passes defensed and one interception.

In his one season with Detroit in 2020, Undlin worked with DE Romeo Okwara, who finished the year with 10.0 sacks. He was one of four players in the NFL to have at least 10.0 sacks, 10 tackles for loss (11), three forced fumbles and one fumble recovery on the season. LB Jamie Collins Sr. was one of three players in the NFL to produce at least 100 tackles, three forced fumbles, 1.0 sack and an interception in 2020.

Undlin joined the Lions after spending the previous five seasons (2015-19) as the defensive backs coach of the Philadelphia Eagles. In 2019, Undlin's defensive backs registered 82 passes defensed, the sixth-most in the NFL. CB Avonte Maddox (10) and CB Sidney Jones (eight) finished with career highs in the category, with each appearing in 12 games that season. The defensive backs as a whole also racked up 7.5 sacks, which were tied for the most among safeties and cornerbacks. The 2018 Eagles defensive backs were led by S Malcom Jenkins, who was selected to the Pro Bowl after he registered 93 tackles, eight passes defensed, three forced fumbles, one fumble recovery, one interception and 1.0 sack.

In 2017, the Eagles defense accounted for the fourth-most takeaways (31) and interceptions (19) in the NFL as Philadelphia defeated the New England Patriots, 41-33, in Super Bowl LII. The year prior, Philadelphia ranked sixth in the NFL in first downs allowed (300) and returned three interceptions for touchdowns, which was tied for the third-most in the NFL. Undlin coached S Rodney McLeod, who in his first season with the team led the Eagles with a career-high 117 tackles, to go along with career-highs in interceptions (three) and passes defended (10).

In Undlin's first year in Philadelphia in 2015, the Eagles defense ranked 10th in the NFL in total takeaways (26) and interceptions (15). Jenkins earned his first trip to the Pro Bowl after posting a team-high 120 tackles, 15 passes defensed along with three forced fumbles. The Eagles were also one of just five teams to have three defensive backs (Jenkins, CB Byron Maxwell and CB Nolan Carroll) register at least 10 passes defensed on the year.

Prior to his time with the Eagles, Undlin was the defensive backs (2013-14) and defensive quality control coach (2012) with the Denver Broncos. In 2014, the Broncos finished the regular season ranked third in total defense (305.2 yards per game), with CB Chris Harris Jr., CB Aqib Talib and S T.J. Ward each earning selections to the Pro Bowl. Denver ranked first in the NFL in opponent's yards per attempt (6.02) and fourth in passes defensed (91) that season. The 2013 Broncos defense recorded the fourth-most passes defensed (97) in the NFL, as Denver reached Super Bowl XLVIII. In 2012, Undlin worked as a quality control coach with the Broncos defense, which finished third in the NFL in pass defense (199.6 yards per game) and was the only unit in the NFL that did not allow a 300-yard passer.

Undlin went to Denver following three years with the Jacksonville Jaguars, starting as a defensive assistant (2009) before being promoted to defensive backs coach (2010-11). He also spent four seasons with the Cleveland Browns as the team's defensive quality control coach (2005-06), secondary/assistant special teams coach (2007) and defensive backs coach (2008). As the defensive backs coach in 2008, the Browns defense finished second in the League with 23 interceptions.

Undlin first entered the NFL with the New England Patriots in 2004 as a defensive assistant, working with the team's secondary. Undlin was part of the Patriots staff that finished with a 14-2 record and defeated the Philadelphia Eagles, 24-21, in Super Bowl XXXIX.

From 1998-99, Undlin first entered the coaching ranks as the linebackers coach at his alma mater, California Lutheran University, before he was promoted to defensive coordinator for three seasons (2000-02). He then joined the Fresno State staff as a graduate assistant (2003) where he coached defensive backs.

Undlin played defensive back at California Lutheran from 1990-94 and registered 12 interceptions, the third-most in school history. In 1993, he was part of a California Lutheran team that finished third in the Southern California Intercollegiate Athletic Conference (SCIAC) for the first time in school history. A native of Sauk Centre, MN, Undlin and his wife, Amy, have one son, Caden, and two daughters, Brooke and Taylor.