On 20 November 2017, Cho scored twice in a 3–0 win over Hwacheon KSPO in the second leg of the WK League final. She finished the 2017 season with three goals and two assists in 27 appearances and won her fourth league title.
On 29 January 2016, Cho joined INAC Kobe Leonessa on loan and was given the number 16 shirt. On 26 March, she made her debut in a 3–1 win over Konomiya Speranza Osaka-Takatsuki. On 11 June, she scored twice in a 6–0 away victory against Konomiya Speranza Osaka-Takatsuki in the Nadeshiko League Cup. On 25 December, she converted a penalty in INAC Kobe Leonessa's penalty shootout win over Albirex Niigata in the 2016 Empress's Cup Final, helping the club to its sixth Empress's Cup title. Cho finished the season with two goals in 27 appearances in all competitions. On 12 January 2017, it was announced that Cho had returned to Hyundai Steel Red Angels.
In December 2018, South Korean media reported that Cho had signed for West Ham United Women of the English FA Women's Super League. Cho So-hyun was officially announced as a West Ham player on 13 January 2019 via the club website where she was quoted as saying "It's always been my ambition to play in England, so this is a very exciting time for me. It's a big league, and to be signing for a big club like West Ham with all the history, makes it even more special." Cho made her debut on the same day coming on as a second-half substitute against title challengers Manchester City. In February 2019 Cho provided both assists for Alisha Lehmann as West Ham beat Reading 2–1. Cho made her Women's FA Cup debut on 3 February 2019 in a 3–1 home victory over Blackburn Rovers. On 14 April 2019 West Ham reached their first FA Cup final by defeating Reading after a penalty shoot-out. With the scoreline deadlocked at 1–1, Cho scored the decisive penalty to send West Ham to Wembley. On 6 July 2020 it was announced Cho had signed a new two-year contract with West Ham.
International career
Cho captained South Korea at the 2015 FIFA Women's World Cup in Canada. In their final group match Cho scored a vital equaliser against Spain. They would go on to win the match and finish second in their group which saw them qualify for the knockout stages. It was the first time South Korea had progressed to the round of 16. In 2015, she was named the KFA Footballer of the Year. In April 2018 Cho scored twice against the Philippines at the 2018 AFC Women's Asian Cup, a win which saw South Korea qualify for the 2019 FIFA Women's World Cup. On 17 May 2019, Cho was officially announced in the 2019 World Cup squad and would again captain the team. Despite South Korea losing their second group stage match to Nigeria, Cho was statistically the best player on the pitch according to football analytics site Twelve Football.
