According to Fabrizio Romano, the Spanish full-back's new deal at Spurs will take him to 2031, plus the option of a further year.
Porro was offered a high wage hike earlier this week, making him one of Tottenham's highest-paid players, and now it appears he's accepted those terms.
In a difficult campaign for the north London side, the 26-year-old was one of the few standout performers as a right wing-back, posting eight goal involvements in 47 matches across all competitions.
That contribution helped Tottenham avoid relegation to the Championship after scraping a 17th-place finish for the second year running.
Under Roberto De Zerbi, the Lilywhites will be looking up the table rather than down as they aim to qualify for Europe next season.
A new contract for Porro signals their intent, as does the addition of Andy Robertson and Marcos Senesi, two established Premier League defenders.