On 30 August, after receiving a work permit, Liverpool announced that they had signed Coates on "a long-term contract" for an undisclosed fee, reported to be around £7 million.

On 21 March 2012, he scored his first goal for Liverpool against Queens Park Rangers, with a scissor kick from the edge of the box in the 3–2 loss at Loftus Road.

[17] Coates had to fill in at left back in the Tyne-Wear derby against Newcastle on 21 December after Anthony Réveillère suffered an injury in the warm up, but coped well as Sunderland won 1–0.

[22] On 28 January 2016, Coates signed for Sporting CP on loan until the end of the season, as new Black Cats manager Sam Allardyce sought to balance the books.

[23] He made his debut on 8 February in a goalless home draw with Rio Ave,[24] and totalled 13 matches (all starts) over the season as the Lisbon-based club came second.

[25] On the first day of the 2016–17 season, at home to Marítimo, Coates scored his first goal for the Leões to open a 2–0 win by heading in João Mário's corner kick.

[27] In the Taça da Liga final on 26 January 2019, Coates missed his spot-kick but Sporting prevailed over FC Porto 3–1 in the penalty shoot-out to win their second straight league cup title.

On 30 November 2023, in a 1–1 UEFA Europa League group stage draw away at Atalanta, Coates played his 343rd match for Sporting CP, overtaking Ânderson Polga as the foreign player with most appearances for the Lions.

At the 2013 FIFA Confederations Cup in Brazil, he made one brief substitute appearance in a 2–1 victory against Nigeria and a start in an 8–0 win against Tahiti in the group, as Uruguay finished the tournament in fourth place.

Although injury saw Coates miss out the entire Premier League season, he made a full recovery in time to be selected in the final 23-man squad for the 2014 FIFA World Cup.

He made one appearance as the side reached the last 16, playing two minutes as a substitute for his Liverpool teammate Luis Suárez in the 2–1 group stage victory over England.