Iowa Highway 143 is a state highway which runs north-south in northwestern Iowa. The highway has a length of 12 miles (19 km).

Iowa Highway 143 begins at an intersection with Iowa Highway 3 just over one mile (1.6 km) south of Marcus in Cherokee County. On the northern edge of Marcus, Iowa 143 crosses a Canadian National Railway line. Six miles (9.7 km) north of Marcus, Iowa 143 crosses into O'Brien County. It ends 5 miles (8.0 km) later at an intersection with Iowa Highway 10, 2 miles (3.2 km) north of Germantown and 4 miles (6.4 km) east of Granville.

Originally, Iowa Highway 143 was a short spur route from Iowa Highway 5 to Marcus; but it was extended north to Iowa 10 in 1937. In 1941, the highway extended south to the Woodbury/Cherokee county border near Correctionville. In the early 1960s, Iowa 143 was paved between Marcus and Iowa 10, and the segment south of Iowa 3 / Iowa 5 was turned over to Cherokee County.