Amano signed for five years, $26.25 million, including $10.5 million guaranteed, an NFL source told ESPN. The deal will pay $12 million in the first year and $18 million in the first three years.
"Eugene has come in to his own as a starter for us on a talented line," Titans general manager Mike Reinfeldt said in a statement. "His signing gives us some flexibility moving forward in a couple of different areas, so it was good to get this done and feel good that the play this line has shown over the last couple of years will continue."
Entering his seventh season, Amano has started 41 games, including 31 in the last two years. He was slated to be an unrestricted free agent when the new NFL calendar begins March 5.
Over the last two years, the offensive line has ranked second in the league in rushing yards (4,791) and is tied with Indianapolis for the fewest sacks allowed (27). Last year, the offensive line paved the way for running back Chris Johnson to become just the sixth player in NFL history to gain 2,000 yards in one season.
Additionally, the Titans became the first NFL team to allow 15 or fewer sacks and average more than five yards per carry.
The team also announced on Wednesday that offensive lineman Mike Otto and linebacker Colin Allred agreed to terms on exclusive rights contracts. Both are reserves.
NFL senior writer Adam Schefter and The Associated Press contributed to this report.