Moultonborough is a town in Carroll County, New Hampshire, United States. The population was 4,918 at the 2020 census, up from 4,044 in 2010. Moultonborough is bounded in large part by Lake Winnipesaukee in the southwest and to a lesser extent by Squam Lake in the northwestern corner. The town includes the census-designated place of Suissevale and the community of Lees Mill.