Born in Auckland, New Zealand, Paea grew up on Vavaʻu, Tonga, which was where he played rugby as a young boy. When he was 16, his family moved to the United States, originally to Lawrence, Kansas, where his cousin Chris Maumalanga was playing for the Kansas Jayhawks. After a year, they moved to Provo, Utah, where Paea attended Timpview High School. Playing defensive line at only 240 pounds, he drew little attention by Division I schools, so he decided to enroll at nearby Snow College in Ephraim.
After redshirting his initial year at Snow, he added more than 20 pounds to his frame and started the 2007 season as the No. 2 tackle on the depth chart. Finally drawing the attention of major schools, he transferred to Oregon State in mid-season after graduating from Snow with an associate's degree in December 2007.
As a junior, he registered a team-leading 8.5 tackles for loss and was co-leader for sacks with three. He was named All-Pacific-10 First Team and received the Morris Trophy for the best defensive lineman in the conference.
In February 2010, a YouTube video showed him bench-pressing 225 pounds 49 times.
Paea was invited to the 2011 Senior Bowl, but tore the lateral meniscus in his right knee on the opening practice, causing him to miss the remainder of the event.
Paea was a nominee for the Bill Hayward Athlete of the Year Award at the 2011 Oregon Sports Awards.
Paea was taken with the 53rd overall pick in the second round of the 2011 NFL Draft by the Chicago Bears and on July 29, 2011, he signed a 4-year contract with the Chicago Bears.
In a Sunday Night Football game on October 16 against the Minnesota Vikings, as well as his NFL debut, Paea sacked Donovan McNabb in the end zone for a safety, being the first Bears player to record a safety in his debut since at least 1970.