Two years later, he captained Ireland in the 2006 Under-19 World Cup where he finished as the second-highest overall run-scorer. He has also played for Finchley CC. He is the leading runscorer in U19 Cricket World Cup history with an aggregate of 606 runs.

Morgan made his One Day International debut for Ireland on 5 August 2006 at the European Championships against Scotland. He fell one run short of a century, scoring 99 before he was run out. It was the first time in ODI history that a player had been dismissed for 99 on debut. Only two other batsmen passed 20 as Ireland beat Scotland by 85 runs. His maiden ODI hundred came not long after, on 4 February 2007 against Canada in Nairobi. At the time he was the youngest ever non-subcontinental player to make a century in ODI cricket, a record subsequently beaten by two other players.

Morgan was the first cricketer to score a first-class double century for Ireland, with an unbeaten 209 against the United Arab Emirates in February 2007 at Abu Dhabi. In February 2007, Morgan was named in Ireland’s 15-man squad for the 2007 Cricket World Cup. Although Ireland performed well in the tournament, Morgan struggled personally, scoring just 91 runs from nine innings. In all, Morgan played in 23 ODIs for Ireland, scoring 744 runs at an average of 35.42.

In May 2007, Morgan was named as one of England’s twelfth men for the Lord’s Test versus West Indies, and came on for Matthew Hoggard on the third day. On 16 August 2008, Morgan represented the England Lions in a list A match against the touring South Africans. He scored 47* in an unbeaten partnership of 113 with Samit Patel in the course of England Lions securing a six wicket victory. Morgan was part of the England Performance Programme squad in India in the winter of 2008, although no matches were played as the tour was cancelled after the November 2008 Mumbai attacks. Morgan was also part of the England Lions for the winter tour of New Zealand.

Morgan scored his maiden first-class century for Middlesex on 5 July 2008 at Uxbridge. This was compiled from 250 balls. He achieved this against the touring South Africans before their Test series against England; the innings included three sixes off spinner Paul Harris. Morgan was part of Middlesex’s victorious Twenty20 Cup winning side in 2008. He underlined his growing maturity after leading Middlesex to victory in the County Championship against Kent.

After touring with the England Lions over the winter, it was announced in April 2009 that Morgan was in England’s 30-man provisional squad for the 2009 ICC World Twenty20. This meant that he could not play for Ireland, who were also participating in the tournament. While disappointed to be denied Morgan’s batting, Irish cricket team manager Roy Torrens said “[Morgan’s] made no secret of that fact [wanting to play Test cricket]. So you know, it’s not totally unexpected to us. We realise this is always going to be a problem with our better players playing in England”.

Morgan’s progression towards representing the senior England side continued when in May 2009 he was named in England’s 14-man squad to face West Indies in a three-match ODI series and the 15-man squad for the World Twenty20. Morgan made his England debut in the second One Day International (after the first was abandoned due to rain), and also played in the third of the series. Morgan was not given much of a chance to impress with the bat, due to not coming in to bat until late in the innings, making scores of 2 and 6 not out, but was praised for his athletic fielding.

Morgan took part in the 2010 Indian Premier League (IPL). In the preceding player auction, he was bought by Royal Challengers Bangalore for a sum of $220,000. However, he was frequently in and out of the side and was not given much opportunity. Morgan was purchased by the Kolkata Knight Riders for $350,000 at the 2011 IPL auctions for the next 3 years.

In 2010 Morgan told the Sunday Times that “From the age of 13, I wanted to play cricket for England. I’ve never felt any shame in saying this is what I wanted to do. And the people at home involved in cricket, they were like, ‘Fair play, it’s going to be unbelievable if you make it’. So I’ve never had any shame about this and my father’s never had any shame about it.” He has subsequently stated that his mother is English, and that he has held a British passport since birth. At the time, England was one of the ten full members of the International Cricket Council, while Ireland was an associate member; only full member nations can play a full schedule of international cricket, including Test matches. Ireland were subsequently admitted as full members in 2017.

On the back of his one-day success, he was then included in England’s Test squad for the home series against Bangladesh. With Paul Collingwood rested, he made his debut in the first Test at Lord’s on 27 May 2010. He scored 44 runs in the first innings but was not required in the second innings as England won by eight wickets after making Bangladesh follow-on. In the second Test, he scored 37 runs as England won by an innings and 80 runs.

Morgan was not initially named in England’s squad for the 2011 World Cup as he was suffering from a fractured finger, but was later called up following an injury to Kevin Pietersen. On 11 March 2011 he made his World Cup debut for England, scoring 63 runs in the defeat to Bangladesh, making him only the fourth player to have represented two different nations at the Cricket World Cup. He made 7 in the next match against the West Indies as England qualified for the Quarter Finals. However, they lost to Sri Lanka by ten wickets, although Morgan made 50 off 66 balls.

In 2013, Morgan captained the T20I team against India in the absences of Stuart Broad, who was out injured. He only made 5 in the first game but made an unbeaten 49 in the second as England won by 5 wickets to level the series. Morgan was praised for captaincy and many pundits suggested he would lead England on a permanent basis in the future.

In 2014, Morgan decided not to enter IPL 2014 due to England playing an ODI series against Sri Lanka at home when IPL took place.

On 19 December 2014, 2 months before the 2015 ICC Cricket World Cup, it was announced that Cook had been removed as one-day captain due to poor form, and replaced by Eoin Morgan.

In 2015, Eoin Morgan decided to play the Indian Premier League and was bought by Sunrisers Hyderabad for $150,000. During the tournament he missed the England ODI game against Ireland. He also played 7 games for the Sunrisers in IPL 2016.

In 2017 IPL Auctions, he was bought by Kings XI Punjab for Rs. 2 Crore. He played until 30 April before returning to England for a training camp.

Morgan played in the Pakistan Super League (PSL) for the Peshawar Zalmi in the 2017 season. He was bought in for US$140,000 in Platinum Category.

In October 2018, he was named in Tshwane Spartans’ squad for the first edition of the Mzansi Super League T20 tournament. In July 2019, he was selected to play for the Dublin Chiefs in the inaugural edition of the Euro T20 Slam cricket tournament. However, the following month the tournament was cancelled. In the 2020 IPL auction, he was bought by the Kolkata Knight Riders ahead of the 2020 Indian Premier League. During the season, Morgan was appointed KKR’s captain.

In March 2018, the ICC named Morgan as the captain of a World XI team to play a one-off T20I fixture against the West Indies at Lord’s in May 2018. He had to withdraw from the team because of a broken finger. On 10 June, he captained England when they lost to Scotland by six runs, at The Grange Club in Edinburgh.

On 19 June 2018, during the third match of the home ODI series against Australia, Morgan surpassed the record of Ian Bell as the all-time leading run scorer for England in One Day International matches. In the same match England posted the highest ever ODI total of 481/6, with Morgan breaking another record: that held by Jos Buttler for the fastest ever fifty by an Englishman in ODIs. (21 balls)

In April 2019, he was named as the captain of England’s squad for the 2019 Cricket World Cup. In the opening match of the World Cup, against South Africa, Morgan played in his 200th ODI match for England, and scored his 7,000th run in ODIs. On 14 June 2019, in the match against the West Indies, Morgan played in his 300th international match for England.

On 18 June 2019, in the match against Afghanistan at Old Trafford, Morgan scored 148 from 71 balls. His innings included 17 sixes, the most sixes by an individual in an ODI innings; his team scored 25 sixes in total, the most sixes by a team in an ODI innings. Morgan’s century came from 57 balls, the fastest by an England batsman in a Cricket World Cup match. On 21 June 2019, in the match against Sri Lanka, Morgan scored his 9,000th international run for England.

On 14 July 2019, led by Morgan, England won the World Cup for the first time, beating New Zealand in the final on boundaries after the match and super over were tied.

In January 2020, Eoin Morgan was named as the captain for Middlesex’s T20 team for the 2020 Vitality Blast campaign. “I’m delighted to be awarded the T20 Captaincy. The role is one that I have really enjoyed. We’ve got an exciting group of players here at Middlesex, with plenty of talent and a good blend of youth and experience, and I’m really looking forward to helping the club build on the improvements we made in this format last year,” Morgan’s statement read upon assuming the captain’s role.

On 29 May 2020, Morgan was named in a 55-man group of players to begin training ahead of international fixtures starting in England following the COVID-19 pandemic. On 9 July 2020, Morgan was included in England’s 24-man squad to start training behind closed doors for the ODI series against Ireland.