Hoilett progressed through Blackburn's youth system before signing his first contract at the age of 16. However, he suffered a setback when he was initially unable to earn a work permit to play in the United Kingdom. In order to qualify for one in future, Blackburn looked to loan Hoilett to a club in another European country, with the player rejecting possible moves to Belgium and France. Hoilett's first match in the starting eleven was against
1899 Hoffenheim on 9 March 2008. Hoilett scored his only goal of his loan campaign on 18 May 2008, against
Borussia Mönchengladbach in what would be his final game for the club. Paderborn were later relegated, ending the
2007–08 2. Bundesliga season in 17th position. Hoilett was loaned to another German club in the
2. Bundesliga,
FC St. Pauli, for the
2008–09 2. Bundesliga season. He made his debut for the
Hamburg-based side against
Greuther Fürth on 22 August 2008. He scored six times during his loan campaign with braces against
Alemannia Aachen and
Hansa Rostock, as well as individual goals against
1860 Munich and
1. FC Kaiserslautern. His final game would come in the form of a 1–0 loss against
Rot Weiss Ahlen on 3 May 2009. St. Pauli finished the season in eighth place.
Blackburn Rovers and
Arsenal at Ewood Park on 17 September 2011 In January 2009, Hoilett's home club Blackburn again applied for him to receive a
work permit for him to play football in England. In the summer of 2009, Hoilett was granted a work permit on appeal, allowing him to continue his fledgling career in England at the
Premier League level with Blackburn. Blackburn chose not to send him to a third loan spell in Germany, rejecting an approach from
Mainz 05. After impressing during the club's pre-season schedule, Hoilett made his debut for Blackburn in the opening day of the
2009–10 season as a late substitute in place of
El Hadji Diouf during a 2–0 defeat to
Manchester City. He was named in the starting line-up for the team's following match and scored his first competitive goal for Rovers in a 3–1
League Cup win over
Gillingham on 25 August 2009. His performances in the early stages of the campaign prompted the club to open talks over a contract extension as Hoilett was in the final year of his original deal. Hoilett was involved in Blackburn's dramatic League Cup win against
Chelsea on 2 December 2009. Coming on as a second half substitution, he won a stoppage time penalty which
Benni McCarthy converted to put Rovers 3–2 up, before
Paulo Ferreira equalised in the 122nd minute. However, Hoilett converted the fifth penalty to help Rovers to a 4–3 shoot-out win and a place in the semi-finals. He then started his first league match on 12 December against
Hull City, playing the full 90 minutes in a 0–0 draw at the
KC Stadium. On 25 February 2010, with his contract due to expire in June 2010, Hoilett ended speculation regarding his future at the club, by signing a new two-and-a-half-year deal with Blackburn, keeping him at the club until the summer of 2012. He finished the season having made 27 appearances in all competitions, scoring once. Hoilett made his first Premier League appearance of the
2010–11 season on 21 August 2010, coming on for
Nikola Kalinić in the 84th minute in a 2–1 defeat at
St Andrew's against
Birmingham City. Hoilett scored his first goal of the 2010–11 season in the 1–0 victory over
Queens Park Rangers in the
FA Cup third round. in 2012Hoilett scored his first league goal on 23 January 2011, in a 2–0 home victory against
West Bromwich Albion at
Ewood Park, converting in the 47th minute from a Nikola Kalinić assist. On 12 February 2011, he made his fortieth Premier League appearance for Blackburn when he featured against
Newcastle United in a goalless draw, and was replaced at half-time due to a slight hamstring strain by
Morten Gamst Pedersen. On 5 March, he scored his third goal of the season in a 3–2 defeat against
Fulham in the 65th minute, away at
Craven Cottage. He was replaced by debutant
Rubén Rochina after 82 minutes. Hoilett's next goal came in the following game, a last gasp equaliser from a header against
Blackpool in a 2–2 home draw. On 9 April 2011, Hoilett scored in the 1–1 draw against Birmingham City before half time, but was injured in the 68th minute, being replaced by Australian
Brett Emerton. Hoilett scored his fifth league goal of the campaign with an individual effort, coming in a 3–2 win against
Wolverhampton Wanderers at
Molineux Stadium on the last day of the season. On 11 September 2011, in a game between Blackburn and
Fulham, he was involved in a collision with
Mark Schwarzer which resulted in a head injury for Hoilett. He was eventually stretchered off and Schwarzer received a yellow card. Hoilett scored Blackburn's controversial second goal in their 3–3 draw with
Wigan Athletic, after teammate Morten Gamst Pedersen seemed to dribble the ball straight from a corner before firing in a low cross for Hoilett to head home from two yards. In January 2012, Hoilett was named one of the thirteen players to watch in 2012 by world football governing body
FIFA. In the
2011–12 season, Hoilett had the most dribbles per game among all Premier League players.
Queens Park Rangers in November 2014 After refusing a contract renewal with Blackburn Rovers, Hoilett joined Queens Park Rangers on 27 July 2012, for a fee decided by tribunal. He signed a four-year contract. He scored his first goal for QPR in a 2–3
League Cup defeat to
Reading on 26 September 2012. On 2 March 2013, Hoilett set-up teammate
Loïc Rémy and played a crucial part in a 2–1 win over
Southampton. A combination of injuries and poor form meant that Hoilett had a frustrating first season at QPR, which resulted in relegation to the
Championship. Hoilett scored his first goal of the
2013–14 Championship season in a 1–1 draw with
Huddersfield Town. Four months later, he scored his second goal of the season in a comfortable 3–0 win over
AFC Bournemouth at
Loftus Road. In QPR's 1–0 victory over
Derby County at
Wembley Stadium in the
Championship play-off final, Hoilett grabbed an assist for the only goal of the game, when he crossed for
Bobby Zamora to score in the 89th minute, as QPR gained promotion back to the Premier League after an absence of one season. After failing to agree a new contract with QPR at the end of the 2015–16 season, Hoilett left the club following the expiry of his current deal.
Cardiff City Following the appointment of
Neil Warnock as manager, Hoilett signed with
Cardiff City on 6 October 2016, becoming Warnock's first signing at the club. Hoilett scored his first goal for Cardiff during a 3–2 victory over Huddersfield Town on 19 November 2016. Hoilett was offered a new contract following the club promotion. On 26 June 2018, Hoilett signed a three-year contract in the Welsh capital. He scored his first Premier League goal since 2012 in a 2–1 comeback win over Wolverhampton Wanderers on 30 November, which BBC Sport called a "fabulous first-time effort from 25 yards". On 9 May 2021, Hoilett announced his departure from Cardiff City at the end of his contract via Instagram. He had spent five years with the club, amassing 184 appearances across all competitions. His last appearance for the club came on 27 January against
Barnsley in the first game in charge for new manager
Mick McCarthy, but he did not feature at all the rest of the season.
Reading On 19 August 2021, Hoilett signed for
Reading on a one-year contract. His first goal for the club came at the
Cardiff City Stadium on 2 October, the only goal in a win over his former club. During the
2022–23 season Hoilett began featuring at wing-back for the club, earning praise for his performances by coach
Paul Ince, heralding him as "unplayable." He departed the club after their relegation at the end of the season, despite being offered a new contract.
Vancouver Whitecaps FC On 14 September 2023,
Major League Soccer club
Vancouver Whitecaps FC announced they had reached a deal with Hoilett to join the club for the remainder of the
2023 MLS season. He made his debut on September 20, entering the match as a second-half substitute for
Ryan Raposo in an eventual 4–1 defeat to the
Houston Dynamo. At the end of the 2023 season, it was announced that the club would not renew his contract.
Aberdeen On 16 February 2024, Junior signed for
Scottish Premiership club
Aberdeen on a short term deal until the end of the
2023–24 season, reuniting with manager Neil Warnock. He made his debut the next day against
Hibernian, entering the match as a substitute in a 2–2 draw and becoming the first Canadian player to ever play for the club. On 30 July, after being offered a new deal he left the club saying that his "time at Aberdeen has come to [an] end, I would like to thank the club for the opportunity and the fans for making my short spell memorable".
Hibernian On 6 August 2024, Hoilett joined
Hibernian on a one-year deal. He scored four goals and assisted five others in 30 appearances during the 2024–25 season, as Hibs finished third in the
Scottish Premiership. On 1 July 2025, Hoilett signed a new one-year contract with Hibs. ==International career==