The Dimasa Kacharis of Dima Hasao, Assam, India have adopted many ethnic ways of using plants, surrounding them, sometimes due to easy availability or poor communication system. But, with modernization, the ethnicity is gradually fading. Thus, it is very important to scientifically document, restore and preserve the knowledge of ethnobotany for greater interest of human society. The extensive interview survey has been carried out among the people of Dimasa Kachari community of 18 villages in Maibang, Langting, Diyungbra and Umrangso of Dima Hasao, Assam from the month of August 2015 to May 2017 following the open-ended questionnaire survey. Sixty-two respondents report a total of 116 plant species and 19 plant parts, of which 74, 60, 22 and 15 species and 13, 12, 11 and 7 plant parts are used for medicinal, edible, cultural and household uses respectively, where some of them are used commonly. These species are of five plant habits—herbs (46 spp.), trees (27 spp.), shrubs (19 spp.), climber (14 spp.) and grasses (10 spp.). A total of 48 ailments (medicinal uses), 11 edible uses, nine cultural uses and ten household uses are recorded. The study reveals a high diversity of ethnically important plants in the ethnic life of Dimasas of Dima Hasao.