The Portuguese side will travel to St. James' Park for a 7pm (BST) kick-off on Thursday, 12th April.
The game will be broadcast live on NUFC TV.
Porto beat Sunderland 5-0 in last year's final and are looking to defend the trophy, having qualified from Group E behind Arsenal - and ahead of Bayern Munich - before beating Liverpool at the quarter-final stage.
Newcastle, meanwhile, were runners-up in Group A with wins against Sparta Prague and PSV, then knocked out local rivals Sunderland earlier this month after a 2-2 draw and an epic penalty shoot-out at the Stadium of Light.
The other semi-final, between Arsenal and Villarreal, will take place at the Emirates Stadium on Tuesday, 10th April.