The Welsh international was set to depart at the end of the season.
However, Dummett has committed his immediate future to Tyneside, as manager Eddie Howe hopes to involve him more in first-team games next term.
Dummett said after renewing: "This is a hugely exciting time for the football club and the city so I'm delighted to be committing another year here and staying at my boyhood club.
"I'm immensely proud that next season will be my tenth involved with the first team and I'm really looking forward to being part of what is a big season to come. Howay the lads!"
Howe added: "Paul is a consummate professional who has given so much to this club and I'm delighted he will be staying with us.
"He is a player and a person I like very much. He leads by example both in the dressing room and on the pitch and I'm pleased to retain someone with his positive influence and defensive capabilities."
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