The La Real academy graduate, from Lasarte-Oria, has become an all-but-undisputed starter in the club's defence since that last renewal, at just 20 years old. He has since been called up by Luis de la Fuente for training sessions ahead of the World Cup and is increasingly attracting interest from major European clubs, factors that persuaded the Basque club to improve his terms once again.
Martín, whose full name is Jon Martín Vicente and whose father Xanti was also a professional centre-back, said he was delighted to have extended his stay.
"I'm happy to be able to stay here, at home, at the club that has given me everything - I've spent my whole life here, since I was 12. The trust and opportunities they've given me since I was young have always been good, I think it's something to be grateful for, and now I've extended my contract keen to repay that trust."
The defender reflected on what it has meant to reach the first team at such a young age.
"I'm young, I'm 20, it's not easy to reach the first team so young and on top of that to be getting the opportunities I'm getting. Last year was very good, we were also able to win a title, and I'm keen to repeat that. I think Barrenetxea, Zubeldia, Oyarzabal or Aritz, who has now left, are examples to follow - I look up to them and try to learn things."
Martín also spoke of his desire to feature in Europe again next season.
"Real Sociedad has shown it's a club that's up there, that plays in European competitions - it's been proving that in recent years and we've achieved it again this year, so I'm keen to have a great year."
This marks the third time Martín has extended his deal with the club in little over two years, having first signed a contract through to 2030 in April 2024 before that agreement was pushed back to 2031 last October. He is now the player with the longest contract of anyone in Pellegrino Matarazzo's squad, a status the club has used to underline its commitment to building around graduates of its Zubieta academy, alongside fellow local products such as Ander Barrenetxea, Jon Pacheco and Beñat Turrientes.
Real Sociedad's willingness to repeatedly improve his terms reflects both his rapid rise and the growing likelihood that his form will continue to draw suitors from elsewhere in Europe.