'The Nuke' posted an average close to 110 in an impressive display that saw him seize full control in the second half of proceedings.
Both players were level at 5-5 until Littler reeled off five legs in a row without allowing Rock a sight at a double.
He extended that streak to seven with Rock stopping the rot, but the holds of throw were with Littler way out in front.
Littler's power scoring kept him going and the defending champion completed a fine performance by winning on his favoured double 10.
"Another brilliant game for myself," Littler told Sky Sports.
"I have gone 109, 113, 109 again (match averages), so I have just got to keep it going.
"Fair play to Josh, he gave me a really good game there. I think it was the third session where I won all five legs.
"I kind of got myself into that lead and I just had to stay there and got the job done."
Littler will maintain his title defence against Dirk van Duijvenbode after the Dutchman managed to survive Gary Anderson 16-13 to begin the night.
The unseeded Van Duijvenbode led 15-8 and was one leg away from victory until former world champion Anderson won five on the spin, which included a 154 checkout.
Van Duijvenbode reset his focus, though, stepping up close out the quarter-final and shutting down Anderson's spirited fightback.