2006-07: Justin Dowling made his WHL debut with two assists in Swift Current's 9-0 win over Regina on January 5th and played four games with the Broncos; spending most of the year with the UFA Bisons midget AAA team in Alberta. He was +3 with three assists appearing in three regular season games and one playoff contest for Swift Current. Dowling scored 23 goals with 38 assists and 24 penalty minutes in 36 regular season games for the Bisons and had 5 goals with 3 assists and 2 penalty minutes in eight AMHL playoff games.
2007-08: Dowling played in 71 of 72 regular season games for Swift Current in his first WHL season. He scored 7 goals with 21 assists and was +2 with 4 penalty minutes as the Broncos finished third in the East Division. Swift Current reached the second round in the playoffs and Dowling scored 4 goals with 3 assists and was +4 with 2 penalty minutes in 12 playoff games.
2008-09: Dowling was the second-leading scorer for Swift Current in his second season with the Broncos. He scored 22 goals and had 44 assists (sharing the team lead with leading-scorer Keegan Dansereau) and was +27 with 16 penalty minutes in 71 regular season games. Swift Current finished third in the East Division and lost to Medicine Hat in a seven-game first round playoff series. Dowling scored 2 goals with 4 assists and was -2 in seven playoff games. He was ranked 101st amongst North American skaters in Central Scouting's final rankings but was not selected in the 2009 NHL Draft.
2009-10: Dowling attended the Pittsburgh Penguins prospect camp in Kitchener in September before returning to Swift Current for his third WHL season. Dowling was the Broncos' second-leading scorer behind Capitals 2009 draft pick Cody Eakin. He scored 32 goals and led the Broncos with 46 assists, finishing +1 with 19 penalty minutes, skating in all 72 regular season games. Swift Current finished third in the East Division and was swept by Brandon in a first round playoffs series. Dowling scored 2 goals with 2 assists and was -2 with 2 penalty minutes in four playoff games.
2010-11: Dowling was invited to the Flyers training camp but was not signed to a contract and made his debut in pro hockey with the AHL's Abbottsford Heat in March 2011 following the WHL regular season. He was a team captain for the Swift Current Broncos. Dowling scored 1 goal with 3 assists and had an even plus-minus with 2 penalty minutes in eight AHL games after signing an Amateur Tryout Contract with the Flames' affiliate. He was the leading scorer for Swift Current in his final WHL season. In 63 games he scored 20 goals with 47 assists and was -11 with 18 penalty minutes. The Broncos missed the playoffs after finishing last in the East Division.
2011-12: Dowling was invited to the Calgary Flames' training camp and signed a two-way AHL contract with Abbotsford — splitting the year between the Heat and the ECHL's Utah Grizzzlies. Dowling scored 1 goal with 1 assist and was -7 with 6 penalty minutes in 22 AHL games with the Heat. He scored 6 goals with 18 assists and was -2 with 6 penalty minutes in 26 regular season games for Utah. Dowling was -3 with no points and 2 penalty minutes in three ECHL playoff games.
2012-13: Dowling signed an ECHL contract with the Idaho Steelheads to start the year and was signed to an AHL contract by the Texas Stars in January following the NHL lockout. In 38 regular season AHL games with Texas he scored 16 goals with 14 assists and was +16 with 4 penalty minutes. Texas finished first in the South Division and reached the second round in the playoffs. Dowling scored 1 goal with 3 assists and was -5 with 2 penalty minutes in nine AHL playoff games. In 34 ECHL games with Idaho he scored 13 goals with 33 assists and was +7 with 16 penalty minutes.
2013-14: Dowling was invited to Dallas' training camp as a free agent and signed an AHL contract with Texas. In his first full AHL season he scored 9 goals with 30 assists and was +11 with 4 penalty minutes in 65 games as Texas finished first in the re-aligned West Division. Dowling signed a two-year, entry-level contract with Dallas on March 26th.
Dallas signed Dowling to a two-year entry-level contract on March 26th, 2014.