Born in Bilbao, Basque Country,[5] Herrera began his career at Real Zaragoza and made his professional debut in the Segunda División in the 2008–09 season.

[citation needed] On 7 February 2011, Herrera agreed to join Athletic Bilbao on a five-year contract for a reported €7.5 million effective as of 1 July.

[8] Herrera made his official debut for Athletic Bilbao on 18 August 2011, playing the full 90 minutes in a 0–0 home draw against Trabzonspor in the 2011–12 UEFA Europa League.

He appeared in 54 official matches and scored four goals in his first season with the Basque club, who reached the finals of both the Copa del Rey and the Europa League.

[11] Manchester United announced on the same day they had completed the signing of Herrera on a four-year contract, pending the receipt of an International Transfer Certificate.

[15] He scored again in United's next game, flicking in Ángel Di María's shot with his heel in their 5–3 defeat to newly promoted Leicester City on 21 September.

[18] Herrera started a Premier League game for the first time since 2 December against Swansea City, scoring United's only goal – his fifth of the season – in a 2–1 defeat.

[19] On 4 April, Herrera scored the first brace of his career to help United beat Aston Villa 3–1; he was also named man of the match for his performances.

[22] His good form continued with a man-of-the-match performance in a 3–0 win against Everton at Goodison Park, in which he scored United's second – heading in from a Marcos Rojo cross, and assisting Rooney's goal in the second half.

[23] On 25 February 2016, Herrera scored his first European goal at Old Trafford – a powerfully converted penalty in the latter stages of a 5–1 win over Midtjylland, in the Round of 32 of the Europa League.

[25] On 23 April, Herrera featured in United's triumph in the FA Cup Semi-final over Everton at Wembley; on as an 87th-minute substitute for Marouane Fellaini with the score tied at 1–1, Herrera played a one-two with Anthony Martial, sending the Frenchman through on goal to score a dramatic injury-time winner to seal a 2–1 win and send United through to the final.

[27] Herrera's role initially remained limited to substitute appearances under new manager, José Mourinho, with Fellaini preferred in midfield alongside world record signing Paul Pogba.

Herrera did, however, start in United's League Cup third round tie versus Northampton Town, and duly registered his first goal of the 2016–17 campaign in his side's 3–1 victory.

[28] He was subsequently retained in the starting line-up for the Premier League game against champions Leicester City, and helped his side register a comfortable 4–1 win.

[29] Herrera was roundly lauded for his performances both against Leicester City and in the games that followed, and was named man of the match for helping Manchester United restrict free-scoring Liverpool to a 0–0 draw at Anfield.

[54][55] Four days later, he scored his first Champions League goal in the competition proper, a low-driven, left-footed shot from the middle of the penalty area in a 1–1 draw against Club Brugge.

[65][66] On 2 March, he issued a statement expressing his concern about the continuous muscle injuries he was suffering throughout the season which were preventing him from having a sustained run of games.