| Winners: | Inverness Caledonian Thistle |
| Promoted: | Inverness Caledonian Thistle |
| Relegated: | Airdrie United, Ayr United |
| League Topscorer: | Adam Rooney (24) |
| Highest Attendance: | 6,289:Dunfermline Athletic 0-2 Raith Rovers (29/08/09) |
| Lowest Attendance: | 703:Airdrie United 1-1 Dunfermline Athletic (09/03/10) |
| Nextseason: | 2010–11 |
The 2009–10 Scottish First Division was the 16th season of the First Division in its current format of ten teams.
Relegated from Premier League to First Division
Promoted from First Division to Scottish Premier League
Relegated from First Division to Second Division
Relegated from First Division to Third Division
Promoted from Second Division to First Division
Teams play each other four times in this league. In the first half of the season each team plays every other team twice (home and away) and then does the same in the second half of the season.
Sources: BBC
| Rank | Scorer | Team | Goals |
|---|---|---|---|
| 1 | Adam Rooney | Inverness CT | 24 |
| 2 | Gary Harkins | Dundee | 15 |
| 3 |  Richie Foran | Inverness CT | 12 |
| Leigh Griffiths | Dundee | ||
| 5 | John Baird | Airdrie United | 11 |
| 6 | Liam Buchanan | Partick Thistle | 10 |
| Derek Holmes | Queen of the South | ||
| Peter Weatherson | Greenock Morton | ||
| 9 | Willie Gibson | Dunfermline Athletic | 10 |
| Jonny Hayes | Inverness CT |
Times are BST (UTC+1)
The ninth placed team in the First Division played the fourth placed team in the Second Division and third placed team in the Second Division played the second placed team in the Second Division. The play-offs were played over two legs, the winning team in each semi-final advanced to the final.
First legs--------
Second legs--------
The two semi-final winners played each other over two legs. The winning team was awarded a place in the 2010–11 First Division.
First leg----
Second leg----
| Team | Kit manufacturer | Kit sponsor | Notes | |
|---|---|---|---|---|
| Airdrie United | Surridge Sports | St Andrew's Hospice | New home and away kits. | |
| Ayr United | Surridge Sports | Paligap | New home and away kits. | |
| Dundee | Bukta | Viga Athletic Clothing (Home), Bukta (Away) | New home and away kits. | |
| Dunfermline Athletic | Puma | The Purvis Group | New home and away kits. | |
| Greenock Morton | Bukta | Millions Chews | New home kit. | |
| Inverness Caledonian Thistle | Erreà | Flybe | New away kit. | |
| Partick Thistle | Puma | Ignis asset management | New away kit. | |
| Queen of the South | Surridge Sports | Peter C Haining Kitchens & Bathrooms | New home and away kits. | |
| Raith Rovers | Puma | O'Connell's Bar and Diner | New home and away kits. | |
| Ross County | Adidas | Highnet | New home kit. |
| Team | Stadium | Capacity | |
|---|---|---|---|
| Airdrie United | 10,171 | ||
| Dunfermline Athletic | 11,998 | ||
| Dundee | 11,856 | ||
| Inverness Caledonian Thistle | 7,711 | ||
| Greenock Morton | 11,612 | ||
| Partick Thistle | 10,887 | ||
| Queen of the South | 6,412 | ||
| Ross County | 6,310 | ||
| Ayr United | 10,185 | ||
| Raith Rovers | 10,104 |