His performances subsequently attracted the attention of Manchester United, and De Gea joined the club in 2011 for £18.9 million, a British record for a goalkeeper at the time.

[14] With first-choice goalkeeper Sergio Asenjo away on international duty at the 2009 FIFA U-20 World Cup, De Gea was called up to the senior team as cover for Roberto.

[15] Roberto's injury meant that De Gea was given his La Liga debut three days later, at home to Real Zaragoza; he gave away a penalty kick in the 19th minute, but immediately redeemed himself by saving Marko Babić's attempt in a 2–1 win.

De Gea began the 2010–11 season by keeping a clean sheet in a 2–0 victory over Inter Milan in the 2010 UEFA Super Cup; in the 90th minute, he saved a Diego Milito penalty kick.

[28] He remained the undisputed starting goalkeeper for the remainder of the season, going on to play in every La Liga match for the team en route to a seventh-place finish.

[32] The next day, he reported that United were making him a contract offer, and the transfer was confirmed on 29 June for a then-British record fee for a goalkeeper of approximately £18.9 million.

Despite being caught out in the first-half by a header from Joleon Lescott and a long-range Edin Džeko strike that put City into a 2–0 lead, United rallied in the second half and won 3–2.

De Gea's improvement in form continued in his next appearance, as he made two notable saves to help his team to a 1–1 draw away at Stoke City,[44] and his overall performance was praised by teammates Patrice Evra and Darren Fletcher.

[58] Due to his involvement in the 2012 Olympics, De Gea missed Manchester United's pre-season tour, but nevertheless returned to the starting line-up for the opening match of the season against Everton.

However, in attempting to claim a cross from Matthew Briggs, a misunderstanding with Nemanja Vidić led to the Serbian defender putting the ball in his own net for Fulham's second goal.

[62] In the next match, a 3–1 win against Sunderland at Old Trafford, De Gea produced an important double-save from Craig Gardner and Stéphane Sessègnon's follow-up.

[71] De Gea was on the receiving end of a controversial aerial challenge by West Ham United striker Andy Carroll that left him "poleaxed", with Ferguson expressing his disbelief at the lack of a red card.

[79] He received the backing of teammate Darren Fletcher, when, in the League Cup semi-final second leg against Sunderland on 22 January 2014, De Gea was deemed to be at fault when he let a weak Phil Bardsley shot past him deep into extra time;[80][81] a Javier Hernández goal soon after left the aggregate score at 3–3, resulting in a penalty shoot-out, where De Gea's penalty saves from Steven Fletcher and Adam Johnson were not enough to help United advance, losing 2–1.

[82] On 19 March, whilst playing against Olympiacos in the first knockout stage of the Champions League as United came from 2–0 down to win 3–2 on aggregate, De Gea made a crucial double-save before half-time which was said to have defied "all known laws of physics and physiology" in a performance described as "magnificent".

[94] Amid rumours of a departure, he said he was "proud" to play for United, and was prompted by Peter Schmeichel and Gary Neville to sign a new contract with the club.

[106] On 31 August, after a summer of speculation, an agreement for a transfer was reached between Manchester United and Real Madrid worth £29 million, including the part-exchange of fellow goalkeeper Keylor Navas.

[109] Twelve days later, in the third round of the League Cup, De Gea captained Manchester United for the first time, wearing the armband for the final nine minutes of their win over Ipswich Town.

[110] In April 2016, while leading the race for the Premier League Golden Glove with 14 clean sheets, De Gea was the sole Manchester United player named in the PFA Team of the Year.

[115] Under new Manchester United manager José Mourinho, De Gea made his first appearance of the season in the FA Community Shield against Premier League winners Leicester City.

[120] On 24 May, he won his third trophy of the season, as Manchester United beat Ajax 2–0 in the Europa League final,[121] despite being an unused substitute to Sergio Romero in that match.

[122] On 17 September 2017, at the fifth match of the Premier League against Everton, De Gea made his fourth clean sheet of the season and 100th overall for Manchester United.

[125] On 11 May 2018, after a 0–0 draw against West Ham, De Gea earned his 18th clean sheet of the season and also secured his first Premier League Golden Glove since he joined Manchester United in 2011.

[128] In March and April, De Gea suffered a run of poor form; being criticised by fans and pundits for mistakes made in losses to Arsenal,[129] Barcelona,[130] Everton,[131] Manchester City,[132] and a 1–1 draw against Chelsea.

[147] However, de Gea continued his error-prone season in United's FA Cup Semi-final tie against Chelsea, where he was directly responsible for one of the goals in a 3–1 defeat.

[155] On 2 February 2021, De Gea played the full 90 minutes and kept a clean sheet in Manchester United's Premier League record-equalling 9–0 home win against Southampton.

On 4 September 2014, he made his first start for Spain, playing the whole 90 minutes against France in a friendly match and conceding a goal from Loïc Rémy to lose 1–0.

He has since shown improvements in his aerial prowess, handling, command of his area, decision making, and ability to come out and claim crosses, in particular after he developed physically and gained more experience, even being described as a "strong presence in the box" by Kyle Diller in 2012.

[33][215][221][222][223] In later seasons, however, Adam Bate of Sky Sports noted in 2019 that De Gea mainly stayed in his area and would come out to sweep up the ball less frequently than other leading keepers in the Premier League; his change in style also drew criticism from Mark Ogden of ESPN in 2020,[224][225] while that same year, Mark Critchley of The Independent opined that De Gea "has never been especially comfortable playing behind a high line, regularly coming out second-best in one-on-ones with opposition strikers.

"[226] Jonathan Wilson in a 2020 article for the Irish Times, also noted that sweeping was not a natural part of his game, and that his tendency to sit deeper with Manchester United in comparison to his position with Spain, who play with a higher line, was one of his reasons for his loss of form since his poor and error–prone performances at the 2018 World Cup.

[226] However, in 2020 his distribution was once again described as being "limited" by Critchley, especially in comparison to other ball-playing goalkeepers in the Premier League,[226] while in a 2018 article for The Guardian, Wilson felt that De Gea's unremarkable passing and lack of confidence with the ball at his feet was one of the reasons for the contrast between his performances with Manchester United and Spain.