Several teams expressed interest in Spaeth after his release from the Chicago Bears on Wednesday for financial reasons.
Spaeth made an official visit to the Cincinnati Bengals on Friday, but ultimately decided to rejoin the organization that selected him in the third round of the 2007 NFL draft.
Spaeth spent the first four years of his NFL career with the Steelers, helping Pittsburgh reach two Super Bowls and win one.
The 6-foot-7 tight end signed with the Bears as a free agent in 2011 and played well in his two years in Chicago. But the Bears cut ties with Spaeth earlier in the week instead of paying him a $500,000 roster bonus. However, it's believed the Bears were open to the idea of Spaeth coming back, albeit at a reduced price.
Considered one of the top blocking tight ends in the league, Spaeth caught six balls for 28 yards and one touchdown last season.