Mannion signed with the Italian club Virtus Bologna on Tuesday, Jordan Schultz of ESPN reports.
Mannion had one steal during Thursday's win over Cleveland.
Mannion posted 19 points (5-12 FG, 5-8 3Pt, 4-4 FT), three assists and a rebound across 29 minutes in Thursday's 141-119 loss to the Kings.
Mannion tallied four points (2-7 FG, 0-2 3Pt), six assists and two steals across 18 minutes off the bench Tuesday in the Warriors' 108-98 loss to the 76ers.
Mannion totaled 10 points (3-7 FG, 2-6 3Pt, 2-2 FT) and four assists across 19 minutes in Monday's loss to the Lakers.
Mannion is in the the starting five for Thursday's game against the Suns, Anthony Slater of The Athletic reports.
Mannion was recalled to the Warriors on Monday, Monte Poole of NBC Sports Bay Area reports.
Mannion (quadriceps) posted 12 points (4-13 FG, 3-9 3Pt, 1-3 FT), 12 assists and four rebounds across 31 minutes in Thursday's 116-111 win over G League Memphis.
Mannion didn't play in Monday's 129-90 win over G League Agua Caliente due to a quad bruise.
Mannion recorded 20 points (7-21 FG, 3-10 3Pt, 3-3 FT), 10 assists and two rebounds across 37 minutes in Wednesday's 111-108 win over G League Canton.