Kentucky Route 3 (KY 3) is a 79.158-mile-long (127.392 km) state highway in the U.S. state of Kentucky.

Kentucky Route 3 originates at a junction with U.S. Highway 23 west of Prestonsburg in Floyd County, Kentucky, United States. The route continues through Johnson, Martin and Lawrence counties to terminate at another junction with U.S. Highway 23 south of Catlettsburg in Boyd County.

From South Catlettsburg to Louisa it follows the original routing of U.S. 23. It intersects KY-180, which parallels I-64, after 6.4 miles (10.3 km). At this intersection, you turn right to stay on KY-3. The road continues 8 miles (13 km) to the Lawrence County line. In Lawrence County, it passes KY-1 and KY-1185, which takes you to Yatesville Lake. It then continues into downtown Louisa toward Inez and on to Prestonsburg.

County	Location	mi	km	Destinations	Notes
Floyd	​	0.00	0.00	US 23 / US 460 – Pikeville, Prestonsburg, Paintsville, Jenny Wiley State Resort Park	Southern terminus
	​	0.051	0.082	KY 1100
	​	1.060	1.706	KY 321 south	Southern end of KY 321 overlap
	​	2.074	3.338	KY 3051 west – Auxier	Southern end of KY 3051 overlap
	​	2.177	3.504	KY 3051 east – Jenny Wiley State Park	Northern end of KY 3051 overlap
	​	2.672	4.300	KY 321 north – Paintsville	Northern end of KY 321 overlap
Johnson	​	4.703	7.569	KY 302 (via KY 3507)	Interchange
Martin	​	18.921	30.450	KY 645 east – Kermit, WV	Southern end of KY 645 overlap; interchange
	​	19.231	30.949	KY 645 west / KY 3412 west (Saltwell Road) – Louisa	Northern end of KY 645 overlap
	Inez	20.457	32.922	KY 40 east (East Main Street) – Kermit	Southern end of KY 40 overlap
		20.617	33.180	KY 40 west – Paintsville, Louisa	Northern end of KY 40 overlap
	​	23.377	37.622	KY 3411 (Fitch Branch Road)	Southern terminus of KY 3411
	Add	24.639	39.653	KY 1884 south (Milo Road)	north terminus of KY 1884
	​	30.177	48.565	KY 292 south (Buffalo Horn Road)	north terminus of KY 292
Lawrence	​	43.028	69.247	KY 644 west	Eastern terminus of KY 644
	​	45.387	73.043	Fort Gay (KY 3S)
	Louisa	45.547	73.301	KY 2566 north	south terminus of KY 2566
		45.800	73.708	KY 2565 south (Pocahontas Street)	Northern terminus of KY 2565
		45.967	73.977	KY 32 west – Paintsville	Eastern terminus of KY 32
		46.686	75.134	KY 2566 south	north terminus of KY 2566
	​	47.501	76.445	US 23 – Paintsville, Ashland, Yatesville Lake State Park Campground
	Five Forks	49.232	79.231	KY 3396 south (Five Forks Road)	north terminus of KY 3396
	​	50.074	80.586	KY 1185 south – Yatesville Lake State Park Marina	Northern terminus of KY 1185
	Fallsburg	53.446	86.013	KY 3398 east (Fallsburg Road)	Western terminus of KY 3398
	​	54.964	88.456	KY 707 north	Southern terminus of KY 707
	​	56.775	91.371	KY 1 north – Webbville	Southern terminus of KY 1
	​	60.125	96.762	KY 1496 west	Eastern terminus of KY 1496
	​	62.427	100.467	KY 3399 south	Northern terminus of KY 3399
Boyd	Boltsfork	65.008	104.620	KY 773 (Bolts Fork)	Northern terminus of KY 773
	Alley	67.987	109.414	KY 854 (Davis Branch)	Southern end of KY 854 overlap
	​	68.261	109.855	KY 854	Northern end of KY 854 overlap
	​	69.736	112.229	KY 966 (Trace Road)	Eastern terminus of KY 966
	Mavity	71.834	115.606	KY 1937	Northern terminus of KY 1937
	​	72.728	117.044	KY 180 west	east terminus of KY 180
	​	79.158	127.392	US 23 to I-64	Northern terminus
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus

Kentucky Route 3 Spur
Location	Louisa
Length	0.053 mi (85 m)

Kentucky Route 3 Spur (KY 3 Spur) is a short 0.053-mile (85 m) spur of KY 3 in Louisa running northeast to the West Virginia border at the Tug Fork of the Big Sandy River, where it continues into that state as West Virginia Route 37.

• "State Primary Road System in Floyd County" (PDF). (37.4 KB)
• "State Primary Road System in Johnson County" (PDF). (32.8 KB)
• "State Primary Road System in Martin County" (PDF). (18.2 KB)
• "State Primary Road System in Lawrence County" (PDF). (13.5 KB)
• "State Primary Road System in Boyd County" (PDF). (25.6 KB)