Ronan made his professional debut as a defenceman with the
Pittsburgh Bankers of the
Western Pennsylvania Hockey League (WPHL) in 1908–09, then would break his contract to leave to play with the
Toronto Professionals, finishing with a few games for the
Haileybury team in the
Temiskaming Professional Hockey League (TPHL). He would stay with Haileybury in 1910 in the inaugural season of the NHA. In 1911, Ronan remained in the NHA after Haileybury returned to the TPHL, as a member of the
Renfrew Creamery Kings in their final season in the NHA. For the
1911–12 season, Renfrew dropped out of the league and its players were dispersed to the remaining clubs in the league by drawing lots. Ottawa picked Ronan after the Wanderers had picked
Cyclone Taylor, and tried to trade Ronan to the Wanderers for Taylor without success. Ottawa's regular centre
Marty Walsh was not playing well and Ottawa tried Ronan out at centre. Ronan blossomed at centre, scoring eight goals in one game and five in another, ending up with 35 goals in 18 games. While a member of the Senators during the 1911–12 and 1912–13 seasons Ronan was also a member of the NHA Eastern All-Stars, managed and coached by
Art Ross, who played a series of exhibition games against an All-Star aggregation from the
Pacific Coast Hockey Association, scoring a total of 8 goals in 9 games over two years. Ronan would play two more seasons with Ottawa before being sold to the
Toronto Shamrocks before the
1914–15 season but did not duplicate his goal totals. Ronan played a season and a half with the Shamrocks and the rivaling Toronto club
Toronto Blueshirts before being dealt to the
Montreal Canadiens, playing on their 1916
Stanley Cup-winning squad, scoring a goal in the deciding game 5 2–1 win over the
Portland Rosebuds. While with the Canadiens Ronan assaulted former Blueshirts teammate
Alf Skinner in a game between the two clubs on January 22, 1916, which had him arrested by police and taken to the Agnes Street station in Toronto, although he was later released on $200 bail. The incident went to trial and Ronan was acquitted of the charge on January 31 before Judge Winchester in Toronto, with Canadiens manager
George Kennedy acting as a witness for the defense. After the 1915–16 season, Ronan signed up with the military where he served until 1918, while being affiliated with the Ottawa Munitions of the Ottawa City Senior Hockey League. He returned to professional hockey and was re-acquired by Ottawa in a trade with the Canadiens in exchange for
Harry Hyland. However, he had lost his offensive skills and was released after eleven games without scoring any goals. ==Career statistics==