Longstaff played as a forward, and scored a goal in Huddersfield's 13-5 victory over Wigan in the Championship Final during the 1911–12 season at Thrum Hall, Halifax on Saturday 4 May 1912, in front of a crowd of 15,000, played as a forward in the 29-2 victory over Wigan in the Championship Final during the 1912–13 season at Belle Vue, Wakefield on Saturday 3 May 1913, in front of a crowd of 17,000, played as a forward in the 3-5 defeat by Salford in the Championship Final during the 1913–14 season at Headingley, Leeds on Saturday 25 April 1914, in front of a crowd of 8,091, and played as a forward, and scored a try in the 35-2 victory over Leeds in the Championship Final during the 1914–15 season at Belle Vue, Wakefield on Saturday 24 April 1915, in front of a crowd of 14,000.
Longstaff played as a forward in Huddersfield's 9-5 victory over Warrington in the 1912–13 Challenge Cup Final during the 1912–13 season at Headingley, Leeds on Saturday 26 April 1913, in front of a crowd of 22,754, and played as a forward in the 37-3 victory over St. Helens in the 1914–15 Challenge Cup Final during the 1914–15 season at Watersheddings, Oldham on Saturday 1 May 1915, in front of a crowd of 8,000.
Longstaff played in Huddersfield's victories in the Yorkshire League during the 1911–12 season, 1912–13 season, 1913–14 season and 1914–15 season.
Longstaff played as a forward in Huddersfield's 19-3 victory over Bradford Northern in the 1913–14 Yorkshire Cup Final during the 1913–14 season at Thrum Hall, Halifax on Saturday 29 November 1913, in front of a crowd of 12,000, and played as a forward (the two tries that are occasionally misattributed to Fred Longstaff, were actually scored by Harold Wagstaff) in the 31-0 victory over Hull F.C. in the 1914–15 Yorkshire Cup Final during the 1914–15 season at Headingley, Leeds on Saturday 28 November 1914, in front of a crowd of 12,000.
Longstaff transferred from Victoria Rangers ARLFC to Halifax, he transferred from Halifax to Huddersfield, he made his début for Huddersfield in the 24-3 victory over Halifax at Fartown Ground, Huddersfield on Saturday 23 December 1911, and he played his last match in the 37-3 victory over St. Helens in the 1914–15 Challenge Cup Final during the 1914–15 season at Watersheddings, Oldham on Saturday 1 May 1915, in front of a crowd of 8,000.
Longstaff won a cap for England while at Huddersfield in 1914 against Wales, and won caps for Great Britain while at Huddersfield in 1914 against Australia, and New Zealand.
Longstaff played as a forward, and scored a try in the "Possibles" 28-15 victory over the "Probables" in the Yorkshire County Trial during the 1913–14 season at Mount Pleasant, Batley on Wednesday 1 October 1913, in front of a crowd of 2,000.
Longstaff played as a forward in Yorkshire's 3-8 defeat by Cumberland in the 1913–14 County Championship during the 1913–14 season at Lonsdale Park, Workington on Saturday 11 October 1913, in front of a crowd of 3,000, and played as a forward, and scored 2-goals in the 19-11 victory over Lancashire in the 1913–14 County Championship during the 1913–14 season at Fartown Ground, Huddersfield on Wednesday 10 December 1913, in front of a crowd of 3,500.
