Terms of the deal were not disclosed, but a source told ESPN NFL Insider Adam Schefter that it is a two-year extension worth $14.7 million, with $8.2 million guaranteed.
Walker is entering the final season of his current contract. The Titans reworked the final year and added two more seasons, meaning he is signed through 2018, the source said.
"We are excited to get this deal done with Delanie," Titans general manager Jon Robinson said in a prepared statement. "He's an integral part of this offense, and he has bought into our philosophy of what Titan football is about. We are looking forward to his continued impact both on the field and in the community in the future."
Walker spent the first seven seasons of his career with San Francisco before signing with Tennessee in 2013.
He led all tight ends with 94 catches last season, and he also set franchise marks with his receptions and 1,088 yards receiving. He has posted career highs for catches and yards receiving in each of his first three seasons in Tennessee.
The Associated Press contributed to this report.