Toeaina was extended through the 2013 season with a three-year deal. Mannelly received a two-year extension through 2012.
Signed off the Cincinnati Bengals practice squad in 2007, Toeaina has set career highs this season in games played (15), starts (10), tackles (28) and sacks (two).
"I got an opportunity, and I had to make sure I took advantage of it, and I guess I did," Toeaina said in a statement. "I'm looking forward to the next three years with the Bears. My family and I love it here in Chicago. We love the coaching staff, we love our teammates and we love the city."
Mannelly is the Bears' all-time leader in games played with 204. Drafted in the sixth round in 1998, Mannelly has handled the long snapping duties in all but three games, and he has played in 136 consecutive games.
"I'm excited I can continue playing for the Bears," Mannelly said in a statement. "With the way the season is going, it could be a chance for two more exciting years. I love the Bears. I've been here for 13 years. Chicago is my home, and I didn't want to leave."