Mukilteo is a city in Snohomish County, Washington, United States. The population was 18,019 at the 2000 census. It is on the shore of Puget Sound, and is the site of a major Washington State Ferries terminal linking it across the water to Clinton, on Whidbey Island.

Mukilteo is one of the most affluent suburbs of Seattle. In 2007, the city had a median income of $83,569. Additionally, like the rest of the Seattle area, house prices have risen rapidly; the median value in 2007 was $567,000. Based on per capita income, one of the more reliable measures of affluence, Mukilteo ranks 29th of 522 areas in the state of Washington to be ranked.