The Reds fielded two entirely different sides in either half in Bangkok, with Adam Bogdan, Joe Gomez and Danny Ings starting the match and James Milner and Nathaniel Clyne coming on at the break.
Lazar Markovic and Mamadou Sakho put the visitors 2-0 ahead at half-time and Adam Lallana and Origi rounded off the scoring in a rain-lashed second half.
Even when the heavy rain came down, Liverpool still managed to dominate proceedings against their Thai opponents, as they had done all match.
On the day that Raheem Sterling left Anfield to join Manchester City, the Reds handed debuts to three of their summer signings in the Thai capital.
The visitors made the ideal start as Joao Teixeira slid a pass through for Markovic and he rounded the keeper to score in the third minute.
Ings, who showed some nice touches during his 45-minute debut, saw a shot saved by the keeper and then had another ruled out after the referee penalised Sakho for a foul.
The All-Stars rarely threatened at the other end and Teixeira and Jordan Rossiter also had efforts saved.
Liverpool eventually added to their advantage late in the half when Sakho headed home from a corner after being left unmarked.
Brendan Rodgers changed his entire line-up at the break but the new-look XI didn’t take long to get into their stride in the pouring rain.
New captain Jordan Henderson chipped a lovely rabona pass through for Lallana, who drilled a low left-footed shot across the keeper.
Origi regularly threatened to add to the tally as he almost turned in a cross from Joe Maguire, hit the post with a low shot from the edge of the box and was then denied by a sharp save from the keeper.
The Belgium international hit the post again with a close-range lob before he finally scored a fourth in the 86th minute when he headed in from a corner.
Liverpool now travel to Australia to take on Brisbane Roar on Friday and then Adelaide United on Monday.