Lakeland is the most populous city in Polk County, Florida, part of the Tampa Bay Area, located …Lakeland is the most populous city in Polk County, Florida, part of the Tampa Bay Area, located along Interstate 4 east of Tampa. According to the 2020 U.S. Census Bureau release, the city had a population of 112,641. Lakeland is a principal city of the Lakeland–Winter Haven Metropolitan Statistical Area.