Manneh scored three goals in Vancouver's 4-1 road win in Seattle on Wednesday. The hat trick was also the first in club history.
Manneh scored his first goal of the game in the 12th minute when he beat Sounders FC defender Jhon Kennedy Hurtado in a foot race and smoothly slotted the ball past goalkeeper Michael Gspurning to make it 1-0.
In the 42nd minute, Young-Pyo Lee collected a loose ball in the Whitecaps' half and sent it down the sideline to Camilo Sanvezzo, who deftly passed it to Manneh in the centre of the field. Manneh ran past the defence and fired a low shot under Gspurning.
He completed the hat trick in the 54th minute when he combined with Daigo Kobayashi at the top of the penalty area and beat Gspurning.
A Whitecap player has won player of the week honours six times this season. Camilo has won three times, including last week. Kenny Miller and Brad Knighton have also won the award this year.