The Champions fell behind inside the opening 30 seconds as a quick free-kick by Jonjo Shelvey saw the former Reds midfielder play Dwight Gayle through on goal. The Magpies forward finished past Alisson, with the goal being confirmed after a lengthy VAR check for offside.
Liverpool were clearly lacking rhythm due to the number of changes to their side, but they showed glimpses of opening the Newcastle defence through Keita and Takumi Minamino.
They began to tighten their grip on the game towards the latter stages of the first half and levelled through a Virgil van Dijk header, with the Dutchman netting his fifth goal of the season.
It was all Liverpool in the second half as they dominated the ball with over 70% possession. Their superiority reaped rewards just before the hour mark as Origi finished from the edge of the box with a brilliant curling effort into the far corner.
With a few minutes left, Mane cut inside from the left and finished past Newcastle goalkeeper Martin Dubravka with a fantastic strike into the top corner to put the icing on the cake for Liverpool.
Slide through our gallery below for all the best photos from the Reds' final day.