The England right-back picked up the injury in the Magpies’ 1-0 win over Aston Villa on Sunday, where Trippier scored the winner via his 35th-minute free-kick.
He was forced to withdraw in the early stages of the second-half before swiftly undergoing an x-ray at the Royal Victoria Infirmary hospital.
And the results on Monday morning confirmed Trippier had fractured his fifth metatarsal in his left foot.
A club statement read: “Newcastle United defender Kieran Trippier is set to be sidelined for the club's upcoming fixtures after fracturing a bone in his foot during Sunday's 1-0 victory over Aston Villa.
“The 31-year-old scored the game's only goal at St. James' Park to help the Magpies to a third successive Premier League win, but had to be substituted early in the second half after sustaining a foot injury.
“Trippier underwent an X-ray immediately after the game and scans have shown a fracture to the fifth metatarsal bone in his left foot.
“Everyone at the club wishes Kieran a speedy recovery.”
Although there is no timeframe over Trippier’s absence, there are fears the 31-year-old could miss the next six weeks of fixtures.
Here’s a look at the matches Trippier could miss as United push to seal Premier League safety:
1. West Ham United (A) - February 19
Newcastle travel to the London Stadium this weekend to face a West Ham side vying for a place in the Premier League top four. Photo: Julian Finney
2. Brentford (A) - February 26
Newcastle's upturn in form has brought Brentford into the relegation picture with just three points separating the two teams. Thomas Frank's side have also played two games extra. Photo: Ryan Pierse
3. Brighton and Hove Albion (H) - March 5
Dan Burn is set to come up against his former club, who sitting nicely in mid-table following a seven-game unbeaten run. Photo: Stu Forster
4. Chelsea (A) - March 13
Another trip to the capital to face the recently crowned Club World Champions. Their hopes of lifting the Premier League title this season are all but over. Photo: Bryn Lennon