List of bus routes in Suffolk County, New York

operates numerous bus routes in Suffolk County, New York, United States; a few in the town of Huntington are operated by Huntington Area Rapid Transit. The Villages of Patchogue and Port Jefferson, also have had their own local jitney bus routes, although budget cuts have forced these villages to take its buses out of service. Some of them are descendants of streetcar lines.
The following tables give details for the routes that primarily service Suffolk County. For details on routes that run into Suffolk County but do not service it primarily, see:

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Suffolk County Transit (SCT)

On October 29, 2023, Suffolk Transit introduced the Reimagine Transit Initiative, a full redesign of the bus network. As part of this redesign, there is daily service system-wide with local buses running weekdays until 10 p.m. and to 8 or 9 p.m. on weekends.

All current routes

Most routes west of Port Jefferson and Patchogue are scheduled with 30 minute headways during weekdays until at least 6:00 p.m. On all routes from Port Jefferson and Patchogue and to the east, including the north-south routes between those two terminals, there are 60-minute headways. All weekday late evening and weekend service runs on 60-minute headways. Route numbers are lower in the western portion of the county and higher in the middle and eastern portions. Odd-numbered routes are generally oriented north to south, with even numbers west to east. Timed connections between routes can be made at Long Island Rail Road stations in Amityville, Bay Shore, Brentwood, Central Islip, Patchogue, and Riverhead, and at the Smith Haven Mall.
SCT also runs two on-demand systems on the South Fork in Southampton and in East Hampton operated by Hampton Jitney and Via Transportation that replaced the former 10A, 10B, and 10C bus routes. The two on-demand zones connect with Route 92 in Southampton, Sag Harbor, and East Hampton. The zones operate 7 days a week between 6 AM and 8 PM, including holidays.
In early June 2024, SCT added a new route, the 56, running between Smithtown Railroad and Kings Park Manor.
In the following table, routes highlighted in red have 30-minute service on weekdays, with non-highlighted routes having 60-minute service.

History of current routes

These current routes are replacements and reconfigurations of the previous routes that were prefixed with an "S" label, although more localized routes did not have the prefix. The prefix denoted Suffolk County, akin to route labeling in other transit systems around the region. See further down in this article for historical information about all of the former routes. Most of the routes listed in this table replaced all of the former routes on October 29, 2023.

Route	History
1	Replaced the S1 with virtually no changes.
2	Replaced the S40 and S20 with service cut back from Sunrise Mall in Nassau County to Amityville LIRR station.
3	Replaced portions of the S23 and S25.
4	Replaced portions of the S33 and 3D.
5	Replaced the S23/29 along Deer Park Avenue, S58 in Smithtown, and 3B in Brentwood.
6	Replaced the S54 with the route modified to serve the Central Islip LIRR station.
7	Replaced the S41, along with portions of the S45 in Brentwood/North Bay Shore.
10	Replaced portions of the S20 and the 1A.
11	Replaced portions of the S27, S45, and 3B in Brentwood/North Bay Shore.
12	Replaced the 2A and 2B.
15	Replaced the S47 with virtually no changes.
17	Replaced the 3C.
51	Replaced portions of the S59, S60, S69 and 7A.
52A/B	Replaced portions of the S57, S60 and 6A. The 52B replaces the S63 in Farmingville.
53	Replaced the S60, S63 and 6B.
55	Replaced the S61.
56	Replaced portions of the S56. Service started June 3, 2024.
58	Replaced portions of the S58, S62, and 8A.
62	Replaced the S62. On September 1, 2024, service was extended along Route 347 from Smith Haven Mall to the New York State Office Building in Hauppauge.
66	Replaced the S66.
77/77Y	Replaced the 7B. On September 3, 2024, service was extended from the Yaphank Correctional Facility to The Boulevard Apartments on William Floyd Parkway, via Yaphank Avenue and the Long Island Expressway.
80	Replaced the 8A.
92	Replaced the S92 with virtually no changes.
110	No changes from previous service.

Former routes - S1 to S94

Most of these routes were reconfigured and replaced by the routes listed above on October 29, 2023 in conjunction with the Reimagine Transit Initiative.

Huntington Area Rapid Transit (HART)

exclusively serves the Town of Huntington. Service runs weekdays and Saturday until 6 p.m. with no service on Sunday. Service is scheduled approximately every 45 minutes on weekdays and 90 minutes on Saturday.

Village of Patchogue Transit

Village of Patchogue Transit was a bus system operated by the Village of Patchogue, with four routes connecting various locations throughout the village.
The system was established in 1975. Sometime after January 13, 2016, bus service was discontinued within Village of Patchogue. The fare to use the system was $0.25.

Former routes

The routes in the table below ran local within the village on weekdays only.

Route	Major streets traveled
1	Rider Avenue, Smith Street, South Ocean Avenue, Gilbert Street, Cedar Avenue, Laurel Street
2	River Avenue and Vicinity
3	West Main Street
4	North Ocean Avenue, Roe Boulevard West, Waverly Avenue, Sunwave Plaza