Mile Oak is a locality forming the northern part of the former parish of Portslade in the northwest corner of the city of Brighton and Hove, England. Now mostly residential, but originally an area of good-quality agricultural land, it covers the area north of Portslade village as far as the urban boundary.

Mile Oak is on the edge of the South Downs and as such has much farmland nearby; the Monarch’s Way and Sussex Border Path long-distance footpaths skirt the edge of the built-up area. The first urban development occurred in the 1930s, and growth continued throughout the postwar era; houses were provided by the council, private builders and housing associations, many of them provided for people occupying substandard houses in the southern part of Portslade.