The young Reds progressed to the knockout rounds of the competition by topping their group with 13 points ahead of Salzburg, Genk and Napoli.
Their reward is a trip to the Portuguese side. The one-off tie is scheduled to be played at 3pm GMT on Tuesday March 3.
Friday's draw mapped out the route to the final, with the winners of the meeting between Liverpool and Benfica to then take on Bayern Munich or Dinamo Zagreb away in the quarter-finals.
U19s boss Barry Lewtas told Liverpoolfc.com: "It will be a bit sunnier than the wind here in Kirkby so that might be a plus! But, to be fair, it's a really good tie.
"Throughout our time at the Academy I've seen the Benfica group quite a few times and we've played them quite a few times in tournaments.
"It's a really good place to play football and it will be a really good game between two good teams, so it's an exciting draw.
"It's not easy to get out of the group in this competition and when you look at the teams who have qualified it's a stellar list and we are one of those sides.
"To get the amount of points we have got during the past two seasons to get out of the group is testament to the boys.
"We've managed to give a lot of different boys exposure to this competition and we've still managed to produce performances and the results to get us where we are.
"I always say to the lads the tournament starts again for us and this time it's knockout football.
"It will certainly be a tough game over in Benfica for us, and for them I hope, but it will be a really good tie."