Doyle has previously played for Chesterfield and Cardiff, as well as Shelbourne, Shamrock Rovers and Sligo Rovers in his native Ireland and Hibernian in the Scottish Premier League.
Doyle was born in Dublin and had a very successful underage career which included playing for the U15 Republic of Ireland national football team. He began his underage club career at then Irish champions Shelbourne, however after three years he left for Cherry Orchard in 2001. He was widely tipped to make the move to English football within a few years as his coaches believed him to be of such a standard.
Following a four-year spell with Dublin club Crumlin United, Doyle returned to Shelbourne just as they were demoted after the 2006 League of Ireland season. He was one of new boss Dermot Keely's first signings and was expected to make a large impact at the club, his time there was cut short and he was released soon afterwards after a disappointing spell for him and the club.
Later on in the 2007 season he signed for Shamrock Rovers. He was promoted from the U21s to the senior squad during the 2007 season, making his début against Waterford United on 10 August 2007. It was speculated that he would move to a different club following former manager Pat Scully's departure however he remained at the club for the 2009 season. He was a substitute for Stephen Bradley in the first game at Tallaght Stadium. Unfortunately for Doyle he did not become a major player under new Rovers manager, Michael O'Neill.
Doyle joined Sligo Rovers on 16 July 2009. He scored on his debut in a 2–0 win over St. Patrick's Athletic. He also scored in the 2009 FAI Cup Final at Tallaght Stadium, however Sligo lost the match 2–1 to Sporting Fingal.
Doyle contributed 8 goals during the successful 2010 season that saw Sligo win both domestic cups, the FAI Cup and the EA Sports Cup. Doyle did very well when forced to play as a centre-forward in the FAI Cup final win and scored one of two penalties in the shoot-out. The 2011 season proved to be his best to date. Early on in the season he was moved into the centre-forward position. He relished the role, scoring a hat-trick in a 3–1 win over Bray Wanderers and at one stage was the league's leading scorer. Doyle ended up scoring 25 goals as Sligo finished second in the league and won the 2011 FAI Cup Final. Doyle scored in the Cup Final penalty shootout, where Sligo ran out victorious 4–1 against Shelbourne. His contract with Sligo expired at the end of the season.
In December 2011, Doyle played in a closed-doors friendly match for Hibernian. The Scottish Sun reported that Aberdeen and Ipswich Town were also interested in signing him. Doyle signed an 18-month contract with Hibernian later that week. He made his first team debut in a 3–1 defeat against Edinburgh derby rivals Hearts. Doyle scored his first goal for Hibs on 7 January, in a Scottish Cup victory at Cowdenbeath. He scored the only goal of the game in the next round of the Scottish Cup, against Kilmarnock on 4 February. Doyle did not start a game for more than two months, until an appearance against St Mirren in late April, where he missed some chances as Hibs lost 1–0. A week later, however, Doyle scored his first league goal for Hibs during a 4–0 victory against Dunfermline, which secured Hibs' place in the SPL.
BBC Radio Sheffield reported on 3 April 2013 that Doyle had agreed to sign for English Football League Two club Chesterfield. Shortly after this announcement, Doyle scored the equaliser in the Scottish Cup semi-final, in which Hibernian overcame Falkirk 4–3 after extra time after having initially been behind 3–0. Doyle played his last match for Hibs in the 2013 Scottish Cup Final defeat by Celtic.
Following his agreement to sign for Chesterfield in April 2013, Doyle formally signed for the club on 31 May. Doyle said that the presence of manager Paul Cook, who had worked with him at Sligo Rovers, was an important factor in his decision to join Chesterfield.
Doyle scored 13 goals in all competitions in his first season with the club, in a season that saw the club promoted to League One and reach the Johnstone's Paint Trophy Final.
Doyle started the season brilliantly scoring seven goals in six games including a hat-trick against Scunthorpe. Three days later Doyle scored another hat-trick this time against Preston. Doyle was named Sky Bet League One Player of the Month for September after seven goals in four games. Doyle continued his form in October scoring three goals in two games against Sheffield United and Bristol City.
On 2 February 2015, Doyle signed for Championship side Cardiff City for an undisclosed fee. He made his début in a 1–1 draw at Hillsborough against Sheffield Wednesday, and later scored his first goal on 21 March against Birmingham City. Doyle went on to score 5 goals in 16 appearances during the remainder of the season.
Despite being a regular in the Cardiff side the previous season, Doyle was sent on loan to Preston North End for the 2015–16 season on 1 September 2015, and made his debut as a substitute against Derby County on 12 September. It took Doyle a month to find the back the net, where he scored the winner against Nottingham Forest.
Doyle signed permanently for Preston for an undisclosed fee on 29 June 2016.
After a very public fight on the pitch between Doyle and Preston teammate Jermaine Beckford during the 2016/2017 season, Doyle fell out of favour and was subsequently loaned out to League Two side Portsmouth until the end of the season.
During the summer of 2017 after returning from an unsuccessful loan spell at Portsmouth, Doyle featured in new Preston North End manager Alex Neil's plans for the 2017/18 season, battling it out with Jordan Hugill and Sean Maguire to lead the line.
On 31 August 2017, Oldham Athletic signed Doyle on loan until 1 January 2018.As of match played 16 September 2017