Petros made his ATP singles debut as a wildcard as well to the main draw of the event at the 2021 Open 13, but lost to Alejandro Davidovich Fokina in the first round in 45 minutes.

At the 2021 ATP Lyon Open, Petros and Stefanos received their sixth wildcard in doubles but lost the first round match.

[5] Petros Tsitsipas again partnering French Luca Sanchez received his fourteenth wildcard to the main draw of the 2023 Open 13 Provence in Marseille.

[8] At the 2023 Wimbledon Championships the brothers lost again in the first round to French teenagers Arthur Fils and Luca Van Assche.

[9] Petros and Stefanos Tsitsipas won their first doubles ATP title in Antwerp, defeating Ariel Behar and Adam Pavlásek in the final.

He competed in the 2024 Summer Olympics in two events: in the men's singles, following the withdrawal of British player Cameron Norrie, where he was defeated 2-0 in sets by Dutch player Talon Griekspoor, and in the men's doubles alongside his brother Stefanos, where they were also defeated 1-2 in sets by the Portuguese pair Nuno Borges and Francisco Cabral.