Anthony Munda's first-half strike sent the young Magpies ahead, rifling the ball home from Alfie Harrison's pass, while Kieran Trippier and Matt Targett were also involved in the derby encounter, both playing the opening 45 minutes at Whitley Park.
With Newcastle head coach Eddie Howe in attendance, United goalkeeper Max Thompson made a string of key stops during the contest before Timur Tutierov's late header denied United's youngsters maximum points in their opening league fixture of the 2024/25 season.
Trippier and Targett, the latter making his first competitive outing since sustaining a hamstring injury in November, were handed starts for United's second-string while the likes of Trevan Sanusi, Harrison and Munda - who all made their Newcastle first-team debuts during pre-season - were named in the starting XI.
Sunderland created the opening goalscoring opportunity of the clash as Ian Poveda drilled an effort from the edge of the box wide of the target.
Harrison, who made his full senior debut during the Magpies' Sela Cup win against Stade Brestois at St. James' Park, went close to firing the hosts ahead as the Keighley-born teenager latched onto a failed clearance from the Sunderland defence before his first-time strike was held by Black Cats goalkeeper Kelechi Chibueze.
In the 20th minute, Newcastle took the lead through Munda as the Cowgate-born midfielder, who signed his first professional contract with his boyhood club last month, latched onto Harrison's pass before cooly rifling the ball into the roof of the net.
Harrison almost doubled United's advantage shortly after as the 18-year-old, capable of playing in central midfield or as a winger, picked up the ball towards the edge of the box before bending a low effort wide of the left-hand post.
Magpies shot-stopper Max Thompson, who spent the first-half of the 2023/24 campaign on loan at Northampton Town, produced a key save to prevent the visitors equalising on the stroke of half-time, denying Zac Johnson's fierce strike with his leg.
In the second-half, Thompson contributed with another important save, beating away Caden Kelly's stinging drive at goal from the edge of the box before the Sunderland substitute tested the Ponteland-born 'keeper shortly after, pushing the midfielder's placed effort from the box away from danger.
In the 87th minute, though, Newcastle's hopes of a clean sheet were dashed as Tutierov, introduced to the field in the latter stages, levelled for the Black Cats after rising high from a looping ball inside the penalty area before heading the ball into the net.
Magpies substitute Josh Donaldson, who signed his maiden pro deal with his boyhood club last month, almost netted a dramatic stoppage-time winner for the hosts as the Gateshead-born strike's close-range shot inside a crowded penalty area was blocked from point-blank range.
Newcastle United Under-21s: Max Thompson, Kieran Trippier (Leo Shahar 46), Cathal Heffernan (c), Ciaran Thompson, Matt Targett (Dylan Charlton 46), Jamie Miley, Anthony Munda, Jay Turner-Cooke, Alfie Harrison (Josh Donaldson 80), Trevan Sanusi (Ellis Stanton 84), Ben Parkinson.
Subs not used: Aidan Harris.
