He played college football for the Michigan Wolverines, and was selected by the Washington Redskins in the second round of the 1999 NFL draft.

Jansen earned Prep Football Report All-Midwest and Detroit News Blue Chip honors as a tight end at Clawson High (Mich.).

He posted 68 career catches and made 202 tackles, four sacks and four interceptions at linebacker to earn Oakland County Defensive MVP honors.

He was Michigan's co-captain as a senior and junior and fortified an offense that posted 4,652 yards en route to the National Championship.

He made a huge impact in mini-camp, training camp and the preseason, impressing coaches with his ability to grasp the Redskins system.

Jansen's blocking helped running back Stephen Davis eclipse the team record with 1,432 yards rushing, third in the NFL and first in the NFC.

Jansen continued to be a solid performer at right tackle, teaming with new right guard Randy Thomas to open up holes and protect Redskin quarterbacks.

He continued his rivalry with Pro Bowl defensive end Michael Strahan by limiting him to two tackles and no sacks.

Jansen suffered a ruptured left Achilles tendon injury in the Redskins' preseason opener on Aug. 9, 2004 against the Denver Broncos.

Jansen was released after a meeting with Redskins owner Daniel Snyder, and head coach Jim Zorn among others.

Jansen stated that the use of illegal substances was on the rise because the use of human growth hormone injections which are not tested for by the NFL.

As of 2018, Jansen has appeared on the weekly Inside Michigan Football TV show, co-hosted by Jim Brandstatter.

In October 2020, Jansen joined sports-talk WXYT-FM in Detroit as morning show co-host with Mike Stone and Heather Park.

Beginning with the 2022 season, Jansen also started calling the University of Michigan Football games for WXYT-FM alongside fellow radio host, Doug Karsch.