Red make their first appearance in the FAI Cup, winning in the First round against Brideville 3–1 before going out to Shelbourne in the next round 5–2. The next year, the club won the Leinster Senior League in only their second year at this level by beating Distillery in a play-off at Tolka Park 3–2 after the teams had finished the league level on points. The team also won the Intermediate Cup, winning 5–1 against Waterford side Tramore Rookies in the final at Dalymount Park, as well as the Metropolitan Cup, beating Queens Park 3–0 in the final at Tolka Park to secure a remarkable treble for the young club. Following this achievement the club was elected to the Free State League on 28 June 1934 along with Waterford as both Shelbourne and Cork Bohemians resigned from the league. Scotsman Bob Preston, ex-Heart of Midlothian, Plymouth Argyle and Torquay United player, managed the team in their first season at the highest level of Irish football with the first game being a 3–1 defeat in the Shield at the Iveagh Grounds in Dublin against St. James Gate. Tommy Callaghan scored Rovers' goal. The team finished third in that season with Gerry McDaid finishing as top scorer. During this season local Paddy Monaghan won two caps for the Irish national team and is still the only man to have achieved this while at the club. The 1936–37 season began in spectacular fashion with Sligo winning their first 11 games and they clinched their first league title by beating Cork 4–3 with two games of the season remaining. Trainer and captain that year was Jimmy Surgeoner in his only season at the club. Top scorer was Englishman Harry Litherland whose record of 19 league goals that season was surpassed by Eoin Doyle in 2011 season scoring 20 league goals. The club also won the Dublin City Cup this year beating Dundalk in the final. Two years later, in 1939, the club reached their first FAI Cup final by beating Dundalk 2–1 in the semi-final. A crowd of 30,601 went to Dalymount Park to see Rovers take on Shelbourne in the final which ended in a 1–1 draw. The replay was held at Dalymount Park 10 days later on 3 May with 28,369 in attendance to see the Dublin side record a 1–0 victory thanks to an early goal. The club were also runners-up