Chris Hogg and Peter Ramage's side will make the short trip to Blackwell Meadows to face Darlington on Saturday, 24th July (kick-off 3pm BST).
They will then take on Gateshead seven days later, on Saturday, 31st July with a 3pm (BST) kick-off at the Gateshead International Stadium.
Both Darlington and Gateshead will be preparing for their National League North campaigns. The Quakers are managed by former Magpies junior Alun Armstrong, while the Heed's boss is ex-Newcastle United defender Mike Williamson.
Ticket details for both matches will be confirmed nearer the time.
More under-23s friendlies will be announced in due course. Last week, United released details of two first-team friendlies, with Steve Bruce splitting his squad to play at York City and Harrogate Town on Sunday, 18th July.
More first team friendlies will also be announced on nufc.co.uk soon.