When Berankis was nine years old he accepted an invitation from Remigijus Balžekas to practise with him at the Šiauliai tennis school (over 200 km from Vilnius).

[9] Berankis got several wildcards to qualifying draws of ATP Challenger and World Tour tournaments (including the Miami Masters) but it took some time for him to win one.

In June, Berankis won the qualification and made his first professional ATP tournament appearance at the Orange Warsaw Open.

In the first round tie against Georgia, he played two singles matches against George Khrikadze[14] and Lado Chikhladze[15] and won both of them in straight sets.

[21] The highest-ranked Lithuanian on the ATP World Tour played in three more Challenger and Futures tournaments before competing in the qualifying draw of the 2010 French Open.

He became the first Lithuanian player to reach the Wimbledon main draw with three straight-set victories, including an upset win over Santiago Ventura in the final qualifying round.

[35] Berankis would finish his European hard-court warmup by losing in the first round of Binghamton challenger to American Jesse Witten 4–6, 4–6.

Immediately following the US Open, Berankis flew back to Lithuania where he played with the Lithuanian Davis Cup team against Slovenia.

After this Berankis would make the quarter-finals of the 2010 Ritro Slovak Open challenger in Bratislava, losing to Stefan Koubek, before going on to win the 2010 IPP Open challenger in Helsinki, beating Michał Przysiężny in the final, to finish the season on a high note, entering the top 100 for the first time and finishing the year at a career-high of 85th in the world, as well as being the youngest player in the top 100.

In the first two rounds of singles draw Berankis defeated Benjamin Becker[44] and Donald Young,[45] then he lost to the eventual champion Milos Raonic, in two tight sets.

[46] Berankis' next tournament was the Regions Morgan Keegan Championships, where he lost to the eventual champion Andy Roddick in the first round, in three sets.

[47] In the first round of the Delray Beach International Tennis Championships, he again lost to the eventual champion Juan Martín del Potro, in straight sets.

[48] At the beginning of March, Berankis came back to Europe to represent Lithuania in the Davis Cup tie against Estonia in Tallinn.

He won both of his singles matches against Jaak Põldma and Jürgen Zopp, the recent one took 20 games in the fifth set and 3 hours 46 minutes in total to decide the winner.

[53] This problem started after Berankis skipped post-match procedures and rushed from the Davis cup match to the airport for 36 hours trip from Tallinn to Indian Wells.

[56] Berankis' back wasn't fully recovered when problems with groin started, so he had to take some time off tennis and take care of his health.

Next week, in the first round of the Aegon Nottingham Challenge Berankis also faced a loss in three sets to the eventual champion Grega Žemlja.

At the BB&T Atlanta Open Berankis went through the qualifying draw and played his first match on ATP World Tour since last July.

He triumphed against Björn Phau, Igor Andreev, Nicolas Mahut and Marinko Matosevic to reach his first-ever ATP 250 final, there he lost to local Sam Querrey.

In January, Berankis took part in the qualifying round of the Australian Open in Melbourne and won his three matches to make the main draw.

[78] Partnering Teymuraz Gabashvili, he won his maiden ATP doubles title at the 2015 U.S. Men's Clay Court Championships.

At the 2015 Citi Open, Berankis defeated Lu Yen-hsun, Pablo Cuevas and Gabashvili to reach the quarterfinals where he lost to American John Isner.

Berankis began the year by defeating Andreas Seppi in the first round of Doha before losing to Andrey Kuznetsov in straight sets.

[79] Berankis was the runner-up at the 2017 Kremlin Cup, the indoor event in Moscow, where he lost against Bosnian player Damir Džumhur.

After losing in the second round of the Australian Open qualifying tournament, Berankis bounced back strongly by winning the Rennes Challenger against Antoine Hoang without dropping a set.

[80] He reached the third round of the 2021 French Open for the first time in his career, also in eight attempts, where he lost again to top seed and eventual champion Novak Djokovic.

At the 2021 Astana Open he reached the semifinal in doubles partnering Artem Sitak, where they lost to top seeds and eventual champions Santiago González and Andrés Molteni.

At the same tournament, he reached the semifinals in doubles partnering Denys Molchanov losing to sixth seeds Aleksandr Nedovyesov and Aisam-ul-Haq Qureshi.

Also as a qualifier, Berankis reached the quarterfinals of the ATP 500 Dubai Open after beating Jan-Lennard Struff and Alexei Popyrin.

[84] At the 2022 Wimbledon Championships, he recorded his fourth main draw win at the tournament defeating former semifinalist Sam Querrey in straight sets.