On 6 July 2018, Buffon signed a one-year contract, with the option for a second year, with Paris Saint-Germain. He made his competitive debut for PSG on 4 August, keeping a clean sheet in a 4–0 win against Monaco in the 2018 Trophée des Champions. Buffon made his Ligue 1 debut on 12 August, keeping a clean sheet in a 3–0 home win over Caen. He was used in a rotational role with Alphonse Areola during the 2018–19 season by manager Thomas Tuchel. After serving a three-match ban in UEFA club competitions, Buffon started for PSG in a 1–1 away draw against Napoli on 6 November, and was beaten by an Insigne penalty; at the age of 40 years and 282 days, he became the second-oldest player ever to make their Champions League debut for a club after Mark Schwarzer, who made his debut in the competition with Chelsea in a 1–0 home victory over Steaua București on 11 December 2013, aged 41 years and 65 days. On 18 December, following an injury to Areola, Buffon played the second half of an eventual 2–1 away win over Orléans in the round of 16 of the Coupe de la Ligue. PSG were eliminated from the competition in the following round after a surprise 2–1 home defeat to Guingamp on 9 January 2019, during which Buffon remained on the bench.