Lambert, the former head coach at Charlotte from 2011 to 2018, will oversee the Boilermakers' defense alongside current co-defensive coordinator Anthony Poindexter. Last month, Purdue fired Bob Diaco after one season as the team's primary defensive coordinator.
Sources said Lambert was a candidate for the Marshall head-coaching vacancy, which went to Alabama assistant Charles Huff.
Marshall's defense led the nation in points allowed (13 points per game), ranked second in yards per game allowed (279.4) and third in yards per play allowed (4.4).
Lambert, 56, also served as Wake Forest's defensive coordinator from 2008 to 2010. The former Kansas State defensive back also spent time at Georgia.
Purdue has revamped its defensive staff this offseason, hiring Mark Hagen for the defensive line and Ron English to help coach defensive backs with Poindexter.