2018 Donegal Senior Football Championship

The 2018 Donegal Senior Football Championship was the 96th official edition of Donegal GAA's premier Gaelic football tournament for senior graded clubs in County Donegal. Sixteen teams competed, with the winner representing Donegal in the Ulster Senior Club Football Championship. The championship began with four groups of four, and continued with a knock-out format. The draws were made on 24 March 2018.

The defending champion was Cill Chartha, which defeated Naomh Conaill by a scoreline of 0–7 to 0–4 in the 2017 final. However, the club had to play the competition without two of its county stars, Patrick McBrearty and Ryan McHugh. On 26 September 2018, it was announced that McHugh had accepted medical advice and would be sidelined for the remainder of the year due to concussion. His injury came while playing for his club in a challenge match against Dublin champions St Vincents in Cavan in late August 2018 — he received a blow to the head during that match. Concussion had also caused McHugh to spend six weeks on the sideline following a 2018 National Football League game (against Kildare or Tyrone depending on which report you read) earlier that year. The injury meant he could take no part in the 2018 Donegal SFC (of which his club was defending champion), news which was worsened when taken in the context of the earlier loss of McHugh's club and county teammate McBrearty to a cruciate ligament injury.

This was the year Oisín Gallen made his senior club championship debut.

This was Milford's return to the senior grade following relegation in the mid-1990s, after claiming the 2017 Donegal I.F.C. title.

On 21 October 2018, Gaoth Dobhair claimed its 15th S.F.C. title by defeating Naomh Conaill by a scoreline of 0–17 to 1–7 at MacCumhaill Park.

Burt was relegated back to the 2019 I.F.C. after just two seasons in the top-flight, when losing its relegation final to newly promoted Milford.

Team changes
The following teams changed division since the 2017 championship season.

To S.F.C.
Promoted from 2017 Donegal I.F.C.
 * Milford - (I.F.C. Champions)

From S.F.C.
Relegated to 2018 Donegal I.F.C.
 * Naomh Muire

Format
The 2018 championship took the same format as previous championships, in which there were four groups of four clubs, with the top two clubs qualifying for the quarter-finals. The club finishing bottom in each group contested relegation play-offs to determine which team would be relegated to the 2019 Donegal Intermediate Football Championship.

Group stage
All 16 clubs entered the competition at this stage. The top two clubs in each group advanced to the quarter-finals, while the club that finished bottom in each group entered a relegation play-off. This year, all clubs played one home match, one away match and one match at a neutral venue.

Group A
Round 1

Round 2

Round 3

Group B
Round 1

Round 2

Round 3

Group C
Round 1

Round 2

Round 3

Group D
Round 1

Round 2

Round 3

Gradam Shéamuis Mhic Géidigh
Odhrán Mac Niallais was named as the recipient of the annual Gradam Shéamuis Mhic Géidigh.