2009–10

Following a successful trial which began in October 2008, despite interest from Scottish Premier League sides Kilmarnock and Motherwell Doolan was signed by Partick manager Ian McCall on an 18-month deal from Auchinleck on 9 January 2009.^[3][4] He made his debut on 10 January 2009, in a 3–0 defeat against Inverness Caledonian Thistle in a Scottish Cup tie.^[5] His first goal for the club came on 24 January 2009, against Queen of the South.^[6]

On 5 February 2010, Doolan was sent out on loan to Clyde to help them try to avoid relegation to the Third Division.^[7] After returning to Firhill, Doolan struggled to cement his place in the starting eleven. However, he subsequently scored a spectacular 92nd-minute goal on the final day of the 2009–10 season against Queen of the South to give The Jags a 1–0 victory.^[8] Doolan was Thistle's top scorer in the 2010–11 season with 18 goals.^[9]

2012–13

During the 2012–13 season Doolan was named as Scottish Football League Player of the Month for March 2013.^[10] On 7 April 2013, he scored in the last seconds of extra-time against Queen of the South in the 2013 Scottish Challenge Cup Final to make it 1–1 and take the match to penalties. Doolan scored with his kick, however Partick Thistle were defeated 6–5.^[11] Doolan's goals helped Thistle secure the 2012–13 Scottish First Division title and subsequent promotion to the new Scottish Premiership.

2013–14

Having gained promotion, Doolan signed a new two-year contract on 21 May 2013.^[12] Doolan scored his first top-flight goal for Thistle in their 3–1 away victory against Ross County at the Global Energy Stadium. Following a poor run of results for Thistle, striker Lyle Taylor was brought in on loan from Sheffield United in the January transfer window. Goals from Doolan and Taylor eventually helped Thistle secure their place in the Scottish Premiership for the 2014–15 season.

2014–15

On 24 May 2014, Doolan extended his contract with Partick Thistle by another two years, keeping him at the club until May 2016.^[13]

Doolan scored his first goal of the 2014–15 season in a 1–0 Scottish League Cup away win to Greenock Morton in the on 26 August 2014. As of 18 October 2014, Doolan had played 203 games and has scored 70 goals in all competitions for Partick Thistle.^[14] On 21 January 2015, Doolan scored four goals against Hamilton Academical in a 5–0 win at Firhill, making him the first Thistle player to score four goals in a top-flight match since George Shaw in 1992, and the first footballer to score a perfect hat-trick in the Scottish Premiership since its formation in 2013.^[15]

2015–16

On 18 January 2016, during the January transfer window, Doolan signed a new contract extension with Thistle to keep him at the club until the summer of 2019. The contract will take him to 10 years of service, and consequently a testimonial year.

2016–17

Doolan scored his first goal of the 2016–17 season in a League Cup group stage tie scoring the winner against Airdrieonians.^[16] He scored his first league goal of the season in a 2–0 away win against Dundee at Dens Park making it 2–0 with a second half strike.^[17] Doolan scored his 100th, and then 101st professional goal for Partick Thistle on 1 April 2017 against Ross County at Firhill.^[18]

2017–18

On 21 April 2018, Doolan scored his 100th league goal in a crucial post-split fixture against Hamilton, making him the first ever Partick Thistle player to score 100 league goals.^{[citation needed]} He played in both legs of the Premiership play-offs against Livingston, scoring his club's only goal in the tie as they were defeated 3–1 on aggregate and relegated to the Championship.^[19]

2018–19: Last season at Firhill

On 1 September 2018, in a league match at Firhill against Greenock Morton, Doolan scored a legitimate goal which was not awarded: the ball struck the underside of the crossbar from his shot, bounced on the solid tube holding the net to the ground, came back out of the goal area and was kicked into touch by a frustrated defender. The minimal movement of the net itself deceived the referee Barry Cook into believing the ball had not crossed the line and he awarded a throw-in, despite the usual reactions of the home team and fans celebrating and the away team starting to walk back to their positions to kick off.^[20] Thistle still won 1–0 despite the error and Doolan was awarded a goal bonus which he donated to charity, with the amount matched by the club.^[21]

A similar incident had occurred at the same end of the same stadium in 1993 when a shot by Dundee United's Paddy Connolly entered the goal and rebounded off the supporting stanchion, but was not awarded even though a defender then caught the ball and handed it to the goalkeeper.^[22]

On 16 March 2019, Doolan was inducted into the Partick Thistle Hall of Fame at Firhill Stadium.^[23] Teammates and friends including Chris Erskine, Steven Lawless, Scott McDonald and Gary Harkins were in attendance, alongside Manager Gary Caldwell. On 23 April 2019, Doolan made his 400th appearance for the club, coming on as a substitute for McDonald against Ayr United.

After a difficult return season to the Championship, with the club having successfully fought off further relegation, on 9 May 2019, manager Gary Caldwell informed Doolan that his contract with Thistle would not be renewed, bringing to an end his 10-year stay at the Firhill club. Partick Thistle chairman Jacqui Low stated: "Kris is, and always will be, a legend at Partick Thistle Football Club. Legend is an overused word but he has earned that title. The service he has given to the club both on and off the pitch is almost unmatched."^[24]

Doolan ended his Thistle career with 401 appearances, 121 goals and 34 assists.