[5] Johnson was born in Sunderland, Tyne and Wear, and brought up in Easington, County Durham, in North East England.

[10] He and his Boro teammates David Wheater, Tony McMahon and Andrew Taylor were part of the squad that won the 2003–04 FA Youth Cup.

[12] Almost six months later, on 10 September, he made his Premier League debut, and first senior start, deputising for the injured fellow academy product Stewart Downing in a 2–1 home win against Arsenal.

[citation needed] He made his second start in the competition against Litex Lovech on 15 December and set up Massimo Maccarone's first goal in a 2–0 win.

[10] Johnson's first goal for Middlesbrough came in a midweek Premier League match away to Bolton Wanderers on 3 May 2006, opening the scoring in a 1–1 draw with "a mazy run from the left flank before curling in a deflected shot".

[17] Later on in the season, he came on as a substitute in the FA Cup replay with Bristol City and played a vital role in seeing Middlesbrough through to the next round by setting up one goal and scoring the winning penalty in the shootout.

[19] In the final match of the season, he scored an 18-yard (16-metre) strike from a loose ball just minutes after coming on as a substitute in Boro's 8–1 victory over Manchester City.

[24] After a bright start to the season, the highly rated youngster became a subject of transfer rumours, but the Boro management insisted that he would not be sold.

[citation needed] On 13 December, he was substituted for Marvin Emnes after picking up a hamstring injury in the 1–0 home loss to Cardiff City[27] but returned to score a penalty against Scunthorpe in a 3–0 win, thus taking his goal tally into double figures.

[citation needed] He scored a brace for the third time in the season when he turned in a man of the match performance against Doncaster Rovers on 26 January to end Boro's winless away streak stretching back to October.

[35] Three days later, he made his first start against Bolton Wanderers on the right side of a three-man attack alongside Carlos Tevez and Emmanuel Adebayor, finishing as the man of the match.

[36] Johnson scored his first goal against Sunderland; he curled a left footed effort into the top corner one and a half minutes into injury time to secure a last-gasp 1–1 draw.

[37] His performance, which earned the man of the match award,[38] led England manager Fabio Capello to publicly praise him and consider him for selection.

[39] On New Year's Day, he scored the winner in the 1–0 win against Blackpool, dedicating his goal to Dale Roberts, his friend and Rushden & Diamonds goalkeeper who committed suicide on 14 December 2010.

[41] After scoring in two 3–0 wins against Inter Milan and League of Ireland XI in the pre-season Dublin Super Cup, he started in Manchester City's first Premier League match of the season against Swansea City, getting an assist as his shot was saved by Michel Vorm and the rebound scored by Edin Džeko.

[51] Sunderland manager Martin O'Neill said "Adding quality players to the squad has been our main aim this summer and Adam certainly fits that bill.

[56] However, his form suffered as Sunderland struggled to one point from the first eight matches, a run that cost manager Paolo Di Canio his job.

[57] After losing his place in the starting line up, the FA Cup third round match with Carlisle United marked a turning point in Johnson's fortunes as he scored a free kick and played a part in both other goals in Sunderland's 3–1 win.

[59] On 11 January 2014, he scored his first career hat-trick and assisted Ki Sung-Yueng, inspiring Sunderland to a 4–1 away win against Fulham which lifted them off the bottom of the table.

[61] On 2 March in the League Cup Final against Manchester City, he assisted Borini for the opening goal in the tenth minute, but Sunderland lost 1–3.

[65] Five days later, Johnson opened the scoring after just 30 seconds against Hull City, but was unable to help the team avoid defeat as they went on to lose 1–3.

[citation needed] In late February 2010, Johnson was named in the senior squad for the first time in Fabio Capello's 30-man shortlist for the upcoming March friendly against Egypt in May, but did not make the final 23.

[81] Johnson made his England debut on 24 May in a FIFA World Cup warm-up match, a 3–1 friendly victory against Mexico at Wembley Stadium.

[83][84] Johnson was named in the starting line-up for the first time, making his full England debut and playing the entire match.

[105] In April 2017 video footage taken inside HMP Moorland appeared to show Johnson talking to fellow inmates about his conviction.

In the footage, Johnson talks about his victim and the fact that he believes his sentence was lengthened due to his position as a professional footballer.

[68][69] He played in 28 games throughout the following 11 months, until he was first dropped from the team on 11 February 2016, and then later sacked by Sunderland, after pleading guilty at trial to two of the four counts put against him.

Allardyce, who had joined the club only in October 2015, claimed that he was not aware of such documents and had always been informed that Johnson was to plead not guilty; a Sunderland press release made the same statement.

[116] She had set up an online group for supporters of his innocence, which reached 1,000 likes before being shut down after being reported by users including North East-based child protection vigilantes Dark Justice.

[119] In February 2016, while giving evidence at his trial, Flounders announced that she and Johnson had separated, claiming that he had confessed to infidelity with other women.