[3] Lansing, the state capital of Michigan, is largely located within the county.

Ingham County is included in the Lansing–East Lansing, MI Metropolitan Statistical Area.

[4] The county consists of gently rolling hills with an elevation ranging between 800 and 1,000 feet above sea level.

The highest point in the county is the top of Teaspoon Hill rising to a height of 1,056 feet above sea level 1.5 miles north of Leslie.

The Sycamore Creek, flowing northwest into the Red Cedar in Lansing, drains much of the midsection of the county.

Most of the southern portion of the county drains south or west into the Grand River.

According to the 2007–2010 American Community Survey 22.8% were of German, 13.2% Irish, 12.5% English and 5.6% Polish ancestry.

The county government operates the jail, maintains rural roads, operates the major local courts, keeps files of deeds and mortgages, maintains vital records, administers public health regulations, and participates with the state in the provision of welfare and other social services.

The 14-member county board of commissioners controls the budget, but has only limited authority to make laws or ordinances due to Michigan's large devolution of local power to cities, villages, and townships.