[4] Liverpool signed Yeşil for a price believed to be £1 million on 30 August 2012 after attracting the attention of manager Brendan Rodgers, who moved quickly to secure the 18-year-old's signature.

He shortly after got his first call-up to the senior squad after that, remaining an unused substitute in a 5–3 UEFA Europa League group stage win away to BSC Young Boys of Switzerland on 20 September.

[5] Six days later, Yesil made his senior debut in the Football League Cup third-round game against West Bromwich Albion, starting in a 2–1 win at The Hawthorns.

[7] On 7 December 2012, after coming back from injury, Yeşil scored his first goal in a Liverpool shirt with a half-volley lob over the goalkeeper to put Liverpool 3–1 up in a 4–1 win over Crystal Palace at The Academy in the U21 Professional Development League, after coming off the bench as a substitute.

In February of the following year, after rupturing his anterior cruciate ligament on international duty with Germany U19, he was sidelined for rest of the season.

[9] Yeşil made his return from injury coming on as a substitute on 19 August 2014 in a U21 Premier League game against Sunderland.

[10] After suffering further injury setbacks, he made his first start in 6 months against Tottenham Hotspur at White Hart Lane on 17 April 2015, scoring twice as Liverpool U21s won 3–1.

His Swiss Super League debut came nine days later, against Grasshopper Club Zürich, replacing Marco Schneuwly for the final fifteen minutes of a 3–3 draw.

Yesil scored a goal in each half to give Panionios a victory at Nea Smyrni Stadium, on the debut of manager Michalis Grigoriou.

Turkish national team head coach Fatih Terim wanted him to play for Turkey.