The 1905–06 Isthmian League season was the first in the history of the Isthmian League, an English football competition.
London Caledonians emerged as champions.
League table
| Season | 1905–06 |
|---|---|
| Champions | London Caledonians |
| Matches played | 30 |
| Goals scored | 86 (2.87 per match) |
1906–07 → | |
| Pos | Team | Pld | W | D | L | GF | GA | GR | Pts |
|---|---|---|---|---|---|---|---|---|---|
| 1 | London Caledonians | 10 | 7 | 1 | 2 | 25 | 8 | 3.125 | 15 |
| 2 | Clapton | 10 | 6 | 1 | 3 | 11 | 13 | 0.846 | 13 |
| 3 | Casuals | 10 | 3 | 4 | 3 | 14 | 14 | 1.000 | 10 |
| 4 | Civil Service | 10 | 4 | 1 | 5 | 16 | 20 | 0.800 | 9 |
| 5 | Ealing Association | 10 | 3 | 2 | 5 | 15 | 19 | 0.789 | 8 |
| 6 | Ilford | 10 | 1 | 3 | 6 | 5 | 12 | 0.417 | 5 |