This is a list of numbered county roads in Lanark County, Ontario. Connecting road segments (some not maintained by the County) are named in parentheses.[1]
| County Road # | Local Name(s) | Northern/Eastern Terminus | Southern/Western Terminus | Settlements served | Additional Notes |
|---|---|---|---|---|---|
| 1 | Rideau Ferry Road | South Street | Rideau Canal | Perth, Rideau Ferry | continues as Leeds & Grenville County Road 1 to Lombardy |
| 2 | Heritage Drive | City of Ottawa limits | Grenville County limits | continues as City of Ottawa Road 2 to Becketts Landing continues as Leeds & Grenville County Road 15 to Merrickville | |
| 4 | Cornelia Street East Roger Stevens Drive | Montague Boundary Road | Smiths Falls | continues as City of Ottawa Road 6 to North Gower | |
| 6 | Althorpe Road Christie Lake Road Sunset Boulevard | County Road 43 | County Road 36 | Althorpe, DeWitts Corners, Glen Tay, Perth | |
| 7 | Fallbrook Road | County Road 511 | County Road 12 | Playfairville, Fallbrook, Balderson | |
| 7B | Townline Road West Townline Road East | County Road 29 | Carleton Place | ||
| 8 | Watsons Corners Road (County Road 511) Herron Mills Road 6th Concession C Lanark | County Road 16 | County Road 511 | Herron Mills, Watsons Corners, McDonald's Corners | |
| 9 | Tatlock Road | County Road 511 | Union Hall, Clayton, Halls Mills, Tatlock | ||
| 9A | McIlraith Road | Tatlock marble quarry | County Road 511 | dead-end road, cut off from continuing to County Road 9 (Tatlock Road) by marble quarry not signed | |
| 10 | Scotch Line South Street (Gore Street East) (Gore Street West) (North Street) Drummond Concession 2 Perth Road (Highway 15) Richmond Road | Ashton Station Road | Leeds County limits | Franktown, Perth, Scotch Line | shares Gore Street East, Perth, with County Road 43 part of a relay of County Roads 10 linking Richmond to Kingston |
| 11 | Wilson Street River Road | County Road 17 | County Road 29 | Appleton | |
| 12 | McDonald's Corners Road Markle Road Mill Street South Street Pine Grove Road | County Road 15 | County Road 36 | Lanark, Playfairville, McDonald's Corners, Elphin | |
| 14 | Narrows Lock Road | County Road 10 | Rideau Canal | Black Lake, Narrows Lock | continues as Leeds & Grenville County Road 14 to Crosby |
| 15 | Fergusons Falls Road | Highway 7 | County Road 511 | Fergusons Falls | |
| 16 | South Lavant Road (County Road 511) Wolf Grove Road Almonte Street | County Road 29 | Frontenac County limits | Lavant, Poland, Hopetown, Middleville, Union Hall, Almonte | |
| 16A | Perth Street Bridge Street Queen Street Martin Street South | County Road 17 | County Road 29 | Almonte | |
| 17 | Blakeney Road Panmure Road Martin Street North (Ottawa Street) Appleton Side Road Cemetery Side Road Derry Side Road | County Road 20 | County Road 10 | Pakenham, Blakeney, Almonte | |
| 18 | Port Elmsley Road | County Road 1 | County Road 43 | Port Elmsley | |
| 19 | Bennett Lake Road | County Road 7 | County Road 36 | Fallbrook, Pratt Corners | |
| 20 | Waba Road (County Road No. 29 North) Kinburn Sideroad | Timmins Road | Robertson Line | Pakenham | continues as City of Ottawa Road 20 to Kinburn |
| 21 | Lally Road Elm Grove Road | County Road 1 | County Road 14 | ||
| 22 | Shaw Road | Lunney Road | County Road 20 | Pakenham Township | minor connecting route |
| 23 | Rosedale Road South | County Road 4 | County Road 43 | Rosedale | |
| 24 | Campbell Side Road 4th Concession Pakenham Bellamy Road Peneshula Road | County Road 20 | Snye Road | Uneeda, Pickerel Bay | |
| 29 | County Road No. 29 North Christian Street County Road No. 29 South Townline Road East McNeely Avenue | Walter Bradley Road | Pakenham, Almonte, Carleton Place | continues as City of Ottawa Road 29 to Highway 417 at Exit 180 | |
| 36 | Snow Road Elphin Maberly Road Maberly Elphin Road Bolingbroke Road | Frontenac County limits | Leeds County limits | Elphin, Maberly, Bolingbroke | continues as Leeds & Grenville County Road 36 to Westport |
| 43 | County Road 43 (Queen Street) (Elmsley Street South) (Elmsley Street North) (Cornelia Street West) (Craig Street) (Gore Street East) (North Street) (Wilson Street West) | Grenville County limits | Smiths Falls, Port Elmsley, Perth | Formerly Highway 43; shares Gore Street East, Perth, with County Road 10; continues as Leeds & Grenville County Road 43 to Merrickville; no longer signed within Perth town limits | |
| 49 | March Road | Golden Line Road | County Road 17 | Almonte | continues as City of Ottawa Road 49 to Highway 417 at Exit 155 |
| 511 | Lanark Road Highway 511 South Street George Street | Renfrew County limits | Perth, Balderson, Lanark, Hopetown | continues as Renfrew County Road 511 to Calabogie (Note: 511 was a former secondary highway before it was downloaded to Lanark and Renfrew counties) | |