On 6 January 2014, Osako joined German sideTSV 1860 Munich for the second half of the 2014–2015 season.[2][3] He scored on his debut, the opener in a 1–1 draw againstFortuna Düsseldorf.[4] He finished the season with 6 goals in 15 appearances.[5]
In June 2014, Osako transferred to1. FC Köln signing a three-year contract. It was reported Kashima Antlers received a transfer fee of €1.5 million while 1860 Munich earned €500,000.[6][5] In October 2016, he agreed a contract extension until summer 2020 with Köln.[7] On 28 April 2018, he played as Köln lost 3–2 toSC Freiburg which confirmed their relegation from the Bundesliga.[8]
On 16 May 2018, it was announced that Osako would joinWerder Bremen for the2018–19 season.[9][10] He scored on his debut on 19 August 2018, netting the first goal with a header in a 6–1 win againstWormatia Worms in the first round of theDFB-Pokal.[11]
In February 2019, he was voted the 2018 Japanese Footballer of the Year.[12]
In May 2018, he was named in theJapan national team's preliminary squad for the2018 World Cup in Russia.[14] In the opening match againstColombia, he scored the second goal for Japan by a header, thus helping Japan become the first Asian team to beat a South American team in the World Cup history. He also appeared for Japan in the2019 AFC Asian Cup hosted by theUnited Arab Emirates. He scored four goals to help them reach the final, where they eventually lost toQatar, 3–1.[15]