Blackburn are one of three clubs taking part in the competition for the first time, while it's the second season that the Magpies have entered.
They reached the semi-finals in 2017/18, losing to eventual winners Porto after beating Sunderland at the last eight stage, having faced Sparta Prague, PSV Eindhoven and Liverpool in the group stage.
United did not enter last year, but got to the final of the Premier League Cup and Premier League 2 division two play-offs as well as winning the HKFC Citi Soccer Sevens in Hong Kong.
Each of the six four-team groups include two Premier League 2 sides and two invited international clubs. The teams all play each other once, either at the Premier League club's home ground or a neutral venue.
The fixtures will be finalised at the clubs' International Cup meeting later this week and will be announced shortly.
The full list of groups is:
Group A Arsenal, Leicester City, Dinamo Zagreb, Villareal
Group B Brighton & Hove Albion, West Ham United, Valencia, Wolfsburg
Group C Blackburn Rovers, Newcastle United, Hertha Berlin, Benfica
Group D Everton, Swansea City, Porto, PSV Eindhoven
Group E Liverpool, Wolverhampton Wanderers, Athletic Club Bilbao, Paris Saint-Germain Group F Derby County, Southampton, Monaco, Feyenoord