The Gulls are now nine points clear in fourth spot with two games remaining to guarantee them a top-four finish.
The side sealed its finals berth with a 2-1 win over Cockburn City at Macedonia Park on Saturday.
The match was goalless in the second half with Sorrento�s Sean Canham knocking in an early match winner two minutes into first half stoppage time.
ECU also won with two first half goals in a 2-1 victory over Subiaco at Rosalie Park. The win moved the Jacks from 11th to 10th.
They face Cockburn City on Saturday, while Sorrento plays Perth Glory.