The undrafted free agent from the University of Manitoba spent his rookie season on the Cleveland Browns practice squad in 2003 before being released that September. Idonije then joined the Bears for the final half of the 2003 season and remained with the team until his departure.
With the Bears Idonije was known for his versatility, including his ability to play defensive and special teams. In addition to being a defensive tackle and defensive end he was successful at blocking field goals and being a gunner on punt returns.
During his nine seasons he recorded 196 tackles, 28.5 sacks, 8 forced fumbles in 134 games.