Interstate 94 (I-94) is a part of the Interstate Highway System that runs from Billings, Montana, to the Lower Peninsula of the US state of Michigan. In Michigan, it is a state trunkline highway that enters the state south of New Buffalo and runs eastward through several metropolitan areas in the southern section of the state. The highway serves Benton Harbor–St. Joseph near Lake Michigan before turning inland toward Kalamazoo and Battle Creek on the west side of the peninsula. Heading farther east, I-94 passes through rural areas in the middle of the southern Lower Peninsula, crossing I-69 in the process. I-94 then runs through Jackson, Ann Arbor, and portions of Metro Detroit, connecting Michigan's largest city to its main airport. Past the east side of Detroit, the Interstate angles northeasterly through farmlands in The Thumb to Port Huron, where the designation terminates on the Blue Water Bridge at the Canada–United States border.

The first segment of what later became I-94 within the state, the Willow Run Expressway, was built near Ypsilanti and Belleville in 1941, with an easterly extension to Detroit in 1945. This expressway was initially numbered M-112. In the mid-1950s, state and federal officials planned an Interstate to replace the original route of US Highway 12 (US 12). By 1960, the length of I-94 was completed from Detroit to New Buffalo. Two years later, the US 12 designation was dropped from the freeway. Subsequent extensions in the 1960s completed most of the rest of the route, including the remaining sections between Detroit and Port Huron which superseded the routing of US 25. The last segment opened to the public in 1972 when Indiana completed its connection across the state line. Since completion, I-94 has remained relatively unchanged; a few interchanges have been rebuilt, a second span was constructed for the Blue Water Bridge, and, in 1987, a plane crashed on the freeway during takeoff from the airport in Detroit. The routing of I-94 is notable for containing the first full freeway-to-freeway interchange in the United States, connecting to the Lodge Freeway (M-10), and for comprising the first complete border-to-border toll-free freeway in a state in the United States. The highway has one auxiliary route, I-194, which serves downtown Battle Creek, and eight business routes. Various segments have been dedicated to multiple people and places.

The entire length of I-94 is listed on the National Highway System, a network of roadways important to the country's economy, defense, and mobility. The freeway carried 168,200 vehicles on average between I-75 and Chene Street in Detroit, which is the peak traffic count in 2015, and it carried 12,554 vehicles immediately west of the Blue Water Bridge in Port Huron, the lowest traffic count in 2015. As the state trunkline highway closest to the lake shore in these areas, I-94 carries the Lake Michigan Circle Tour south of Benton Harbor–St. Joseph and the Lake Huron Circle Tour in the Port Huron area. Sections through the Detroit area are named the Detroit Industrial and Edsel Ford freeways. I-94 in the state is either a four- or six-lane freeway for most of its length; one segment in the Detroit area has up to 10 lanes total near the airport.

I-94 enters Michigan from Indiana south of New Buffalo. The freeway runs northeasterly through rural Michiana farmland in the southwestern corner of the Lower Peninsula and parallels the Lake Michigan shoreline about three miles (4.8 km) inland. I-94 traverses an area just east of the Warren Dunes State Park as the freeway runs parallel to the Red Arrow Highway, a former routing of US 12 named after the 32nd Infantry Division (Red Arrow Division). The freeway crosses its companion highway south of St. Joseph; Red Arrow turns northward carrying the business loop for Benton Harbor and St. Joseph (Business Loop I-94, [BL I-94]). The Interstate curves further inland to bridge the St. Joseph River near Riverview Park. East of Benton Harbor, I-94 meets the other end of BL I-94 at an interchange where US 31 merges onto the freeway. East of the Southwest Michigan Regional Airport, I-94/US 31 meets the southern end of I-196; US 31 departs the I-94 freeway to follow I-196, and I-94 continues its course away from Lake Michigan.

South of Coloma, the trunkline turns eastward and roughly follows the Paw Paw River on a course that takes it south of Watervliet and Hartford. Between the latter two cities, the freeway transitions from northeastern Berrien County into western Van Buren County. It curves around and between Lake Cora and Threemile Lake near the junction with the northern end of M-51. About four miles (6.4 km) further east, I-94 crosses M-40 south of Paw Paw. Continuing eastward, the Interstate runs through Mattawan before entering western Kalamazoo County.

In Texas Township, the freeway enters the western edges of the Kalamazoo suburbs. South of the campus for Western Michigan University's College of Engineering & Applied Sciences in Portage, I-94 intersects US 131. Near the Kalamazoo/Battle Creek International Airport, the Interstate passes into the southeastern corner of Kalamazoo before entering Comstock Township. The freeway intersects the eastern end of Business Spur I-94 (BS I-94) at a partial interchange near Morrow Lake in the township. I-94 continues out of the eastern Kalamazoo suburbs, paralleling the Kalamazoo River through the Galesburg area. Before crossing into Calhoun County on the west side of Battle Creek, I-94 has the only driveway on any of Michigan's Interstate Highways for a gate providing access for military vehicles into the Fort Custer Training Center.

The Interstate enters Calhoun County southwest of the W. K. Kellogg Airport and enters the city of Battle Creek. Immediately east of the county line, the freeway has an interchange with the western end of Battle Creek's business loop. Next to Lakeview Square Mall, I-94 meets its only auxiliary Interstate in Michigan: I-194. I-94 turns to the northwest to round Beadle Lake, intersecting M-294 before spanning the Kalamazoo River. East of the river crossing, the freeway meets an interchange for M-96, M-311, and the eastern end of the Battle Creek business loop near FireKeepers Casino Hotel in Emmett Township. Turning back eastward, the Interstate exits the eastern Battle Creek suburbs and continues to an interchange with I-69 near Marshall; the business loop for Marshall follows I-69 southward.

Continuing eastward, I-94 traverses rural land on the north side of Marshall. The freeway runs north of, and parallel to, the Kalamazoo River through eastern Calhoun County. It angles southeasterly toward Albion before returning to an easterly course on the north side of town. I-94 crosses into western Jackson County before intersecting M-99. From there, it runs generally due east with a jog around Parma. West of the county airport, the Jackson business loop follows M-60 southward, and I-94 travels through the north side of Jackson. North of downtown, US 127 merges in from the north and runs concurrently with I-94 around the city. Southeast of Michigan State Prison, US 127 departs to the south, and I-94 continues eastward through the rest of the county.