All kinetoplastids are basically unicellular but Cephalothamnium forms a sessile colony. All species are heterotrophic and phagotrophic or osmotrophic. The kinetoplastids are common in freshwater, marine and soil. Neobodo or Bodo is one of the commonest flagellate in these environments. Some kinetoplastids are parasitic in animals and lamd plants. Especially some trypanosomes are seriously damage to human and domestic animals (e.g. sleeping sickness and Chagas disease by Trypanosoma, leishmaniasis by Leishmania). Ictyobodo and Cryptobia sometimes damage to fishes. Perkinsiella is unique to live endosymbiotically in amoebae.

The kinetoplastids are naked, but the cytoskeletal microtubules beneath cell membrane are developed. The cell possesses apical depression from which two heterodynamic flagella emerge (sometimes one flagellum is reduced). The flagellum is accompanied with a praxial rod and (sometimes) non-tubular mastigonemes. The posterior flagellum is trailed and sometimes forms undulating membrane. The characteristic feature of the Kinetoplastea is a kinetoplast, a DNA-containing granule located within the single mitochondrion and associated with the flagellar bases. In some species the kinetoplasts are dispersed. The mitochondrial genome is differentiated into maxcircle and minicircles involved with complex RNA editing. Nuclear genomes produce polycistronic mRNA involved with trans-splicing. The cell possesses glycosome in which the glycolytic enzymes are located. Asexual reproduction by means of binary fission. Some species form cysts. Sexual reproduction is unknown.