Born into a family of martial artists, Kubo began playing soccer at the age of five and initially started playing as a defender in elementary school, switching to forward injunior high school.[1] In his second year, he was recruited byKyoto Sanga to join their youth academy. In his third year of junior high, he participated in the National Junior High School Soccer Tournament and representedYamaguchi Prefecture in the National Sports Festival.
In 2009, at the age of fifteen, he joined the U-18 team of Kyoto Sanga and at 16 he was temporarily registered with the first team before returning to the youth squad for the J.League Youth Championship, leading the "Golden Generation" of Kyoto Sanga Youth to the semifinals.[2] In 2011, he was officially promoted to the first team. and made hisJ2 League debut, scoring in his first start. By the end of the season, he had scored 10 goals in 30 league matches, becoming the team’s top scorer at just 17 years old.[3] On 29 December, in theEmperor’s Cup semi-final againstYokohama F. Marinos, Kubo came off the bench and scored a crucial goal in extra time to break the 2–2 deadlock. He would also provide an assist in the game, helping to secure his team’s spot in the final with a 4–2 victory.[4] He scored in the final againstFC Tokyo, coming off the bench as he did in the semi-final. His goal was in vain this time however, as FC Tokyo won the match 4–2.[5][6]
During the 2013 season, he scored his first professionalhat-trick.[7]
On 18 June 2013, Kyoto Sanga announced Kubo's transfer to Swiss clubBSC Young Boys.[8] He made hisSwiss Super League debut on 13 July playing 15 minutes in a 2–0 win against FC Sion at the season opener.[9] In his third match on 28 July, he scored two goals and made one assist coming off the bench against FC Thun in a 3–2 win,[10] and continued to impress with another goal in the fourth match.[11] Although he started only five matches in his first season in Switzerland, he played in 34 league games, scoring seven goals and providing five assists, helping Young Boys finish third and qualify for theUEFA Europa League.
Kubo started the domestic season strong with goals in the opening two matches while playing as an attacking midfielder,[12] but struggled to maintain a starting spot as his coach wanted him to focus more on playmaking rather than scoring. He expressed frustration post-match after coming on as a substitute in matchday 28, stating, "This style of play takes away my strengths. Moving forward, I want to balance team play while still showing my abilities." Given a starting appearance in the following game, Kubo scored the opening goal versusGrasshopper.[13] By season’s end, he had played 27 league matches and started 14, scoring five goals. During the2014–15 Europa League, Kubo helped Young Boys reach the group stage. He debuted in the group stage with an assist in their opening match againstSlovan Bratislava[14] and continued impressing, assisting against Napoli and scoring a crucial brace in the return fixture against Slovan Bratislava, making him the second Japanese player to score twice in a Europa League match afterShinji Okazaki.[15] His team was eliminated in the following round by Everton.
In the2015–16 Champions League season, his team was eliminated in the qualifying round byAS Monaco and dropped into the Europa League playoffs, where they were eliminated byQarabağ FK. Domestically, Kubo had a strong start, scoring two goals in the first round of theSwiss Cup against SC Kriens. He then scored one goal in each of the following three league matches.[16] On 20 April, he scored a brace versusFC Luzern. Although he missed the latter part of the season due to injury, he recorded nine goals and six assists in 29 league appearances, the highest tally since his move.[17] His contributions helped Young Boys finish second again, and he extended his contract until 2020.[17]
During the start of the 2016–17 season, Kubo was about to depart for Brazil with his national team for theOlympics, but was recalled by Young Boys due to injuries in the squad.[18][19] He scored in the first game of the season on 23 July versusSt. Gallen, and played a key role in Young Boys' Champions League qualifying win againstShakhtar Donetsk, scoring twice.[18] Kubo scored in all three Swiss Cup matches that he appeared in, including netting a hat-trick on 18 September. He also scored in three straight league games for the second time for his club.
On 25 January 2017, Kubo was acquired by Belgian clubKAA Gent for a transfer fee of €3.5 million.[20] He had an immediate impact for his new club, scoring a free-kick goal from 27 yards out in his first game.[21] He finished the regular season by scoring five goals in the seven remaining games.[22] His hot form continued into the playoffs, starting all 10 games while scoring six times, ending his season scoring 23 goals across all competitions for both clubs.
In August 2018, Kubo joinedBundesliga side1. FC Nürnberg on loan for the 2018–19 season. While his Gent contract was also extended, Nürnberg secured an option to sign him permanently.[23]
On 9 January 2020, Kubo joinedMLS sideFC Cincinnati as adesignated player.[24] Signed as an attacking player,[25] he made his FC Cincinnati debut against theNew York Red Bulls, on 1 March 2020 and scored his first goal for his new club in the following match.[26][27][28] At the beginning of the 2021 season, Kubo transitioned to become a more versatile position player, tasked with assuming the role of a defensive midfielder.[29][28] On 16 June 2024, after returning from a month-long injury layoff, Kubo scored a hat-trick in nine minutes after coming on as a second-half substitute.[30] He finished with 11 goals across all competition in2024, his highest tally since joining FC Cincinnati, and on 15 July surpassed teammate and Cincinnati-nativeNick Hagglund as the club's all-time leader in appearances.[31] On 26 November 2025, the team announced that they had declined Kubo's contract option.[32]
Kubo has been involved in theJapan National Team from U-16 to U-23 level. He received his first call up to the senior team for the Kirin Challenge Cup, a friendly match againstIceland in February 2012, however he did not feature during the 90 minutes.[33]On 11 November 2016, he made his full international debut forJapan againstOman in the Kirin Challenge Cup 2016.On 23 March 2017, he scored one goal and gave one assist in 0–2 win overUAE in2018 FIFA World Cup qualification. It was his first goal in his third game forJapan.On 28 March 2017, he scored one goal and added two assists in a 4–0 victory overThailand in2018 FIFA World Cup qualification.
A versatile player, Kubo has been deployed as a forward, namely as asecond striker, but has also appeared as adefensive midfielder and as a winger.[34][35][36] Described as very comfortable on the ball, Kubo has also been lauded for his work rate and ability to manoeuvre though tight spaces.[37][38][39][40]