[3][4] While volunteering as a ball boy at the 2013 Davis Cup World Group play-offs, Berkieta was hit in the stomach by a 230 km/h (140 mph) serve from Nick Kyrgios and had to exit the court.

[18][19] Unseeded at the French Open, he reached his first junior Grand Slam final with wins over Izan Almazán Valiente, sixth seed Hayden Jones, qualifier Charlie Robertson, wildcard Moïse Kouamé, and Lorenzo Carboni.

[21] In August 2022, Berkieta made his ITF Men's World Tennis Tour main draw debut as a wildcard at the M25 Poznań.

[22] In August 2023, he made his ATP Challenger Tour main draw debut as a wildcard at the Kozerki Open.

[23] He represented Poland in the 2023 Davis Cup World Group II, where he recorded a win over Xavier Lawrence of Barbados.