The 2017 Longford Senior Football Championship was the 101st running of the Longford GAA's premier club Gaelic football tournament for senior graded teams in County Longford, Ireland since the first County Championship was held in 1890 (100 completed since 1890, 1 started but not completed in 1891). The 2017 tournament consisted of 12 teams, with the winner going on to represent Longford in the Leinster Senior Club Football Championship. The championship starts with a group stage and then progresses to a knock out stage.
Mullinalaghta St. Columba's were the defending champions after they defeated Abbeylara in the previous year's final. In the final, they repeated their victory over the same opponents, retaining their title for the first time ever.
This year St. Brigid's Killashee returned to the senior grade after a 3-season absence since relegation in 2013 after claiming the 2016 Longford Intermediate Football Championship title, However they made the straight drop back down to the middle grade after finishing bottom of their group this year. Fr. Manning Gaels also joined them in the middle tier for the first time in 42 years, after losing their Relegation Play-off final.
The following teams have changed division since the 2016 championship season.
Promoted from 2016 Longford Intermediate Football Championship
Relegated to 2017 Longford Intermediate Football Championship
All 12 teams entered the competition at this stage. Groups A and B each consisted of 4 seeded teams (the previous year's quarter-finalists) with 3 teams from each group progressing to the quarter-finals. Group C consisted of the 5 unseeded teams (seeding based on the previous year's performance). 2 teams from Group C proceeded to the quarter-finals while the bottom finisher was relegated to the 2018 I.F.C. 3rd and 4th in Group C played off in a Relegation final to decide the second team to be relegated.
Round 1:
Round 2:
Round 3:
Round 1:
Round 2:
Round 3:
Round 1:
Round 2:
Round 3:
Round 4:
Round 5:
The top 8 teams from the league stages qualify for the quarter-finals. The winners of Groups A and B are kept on opposite sides of the draw.