On 27 May 2019, Valbuena signed a one-year contract with Greek Superleague club Olympiacos. His first goal for the club, a penalty in a 2–0 win over İstanbul Başakşehir F.K., helped Olympiacos progress to the UEFA Champions League playoffs. His penalty was the only goal of their second match of the 2019–20 Superleague, away to Larissa. After Olympiacos went two goals down at home to Tottenham Hotspur in their first match of the Champions League group stage, Daniel Podence scored just before half-time with Valbuena's assistance and soon after the break, Jan Vertonghen fouled Valbuena for a penalty which he himself converted to complete the comeback.
