He is of Samoan descent. Despite Polamalu's hard-hitting style on the gridiron, he is known off the field as a soft-spoken, Christian family man.

Polamalu is an Eastern Orthodox Christian, having converted through the influence of his wife Theodora. He makes the Sign of the Cross after every play (from right to left, in the Eastern Christian manner, as opposed to the Roman Catholic left to right motion). Among his spiritual activities is a pilgrimage to Orthodox Christian sites in Greece and Turkey, taken in 2007. He seldom gives interviews, but when he does, he often speaks of the role his spirituality plays in his life. Polamalu has said that he tries to separate himself from his profession as much as possible, like not watching football games at home. He prays after each play and on the sidelines.

Polamalu is known for his humble lifestyle. He was raised by his mother's family, hence the name Polamalu. He rarely hangs out with teammates, instead preferring to spend time at home with his wife Theodora, the sister of former Rams tight end Alex Holmes, another former USC player, and best friend Aaron Wesley Shoop. They enjoy surfing together in San Clemente, CA and eating tacos at Sanchos in Tustin, Ca.