The 23-year-old's previous deal ran until 2029 following an extension agreed in January 2025. This latest renewal adds a further year to his commitment and comes amid reported interest from Manchester United, Liverpool, Chelsea, Barcelona and Real Madrid.
Murillo joined Forest from Corinthians in August 2023 for £11 million and has made 114 appearances for the club, becoming one of the most reliable centre-backs in the Premier League. He will miss Sunday's final home game of the season against AFC Bournemouth with a hamstring problem suffered last week, but is expected to be fit for pre-season.
He spoke warmly about the decision to extend.
"This is my second renewal with the club and I'm feeling so happy. It's a dream and it's really important for me, my family and my career. It shows me how important I am for the club and that people have confidence in me. I also want to thank the fans because they are really important not only for me but also the team, and I am feeling so proud."
Global Technical Director George Syrianos added: "Murillo has continued to improve from the moment he arrived here, establishing himself as one of the best players in his position. He is a hugely important player for us and has a big appreciation for Forest and the love he receives from everyone connected to the club."
The renewal comes at the end of a season in which Murillo scored at Anfield in the Premier League and in Istanbul in the Europa League against Fenerbahçe, contributing at both ends of the pitch as Forest secured European qualification for a second consecutive campaign. He has also made his debut for Brazil, earning his first senior cap last year.
Forest are not selling. The contract is the clearest statement they could make.