The low-frequency noise (LFN) sources in ultrathin body (8.7 nm) and buried oxide (10 nm) fully depleted silicon-on-insulator (UTBB FD-SOI) n- and p-channel MOSFETs are analyzed. Both flicker and Lorentzian-type noise were observed, showing a dependence on the channel dimensions and the front/back gate bias conditions. The flicker noise component can be described by the carrier number with correlated mobility fluctuations model considering contribution from both interfaces. The Lorentzian-type noise originates mainly from generation-recombination (g-r) traps in the Si film, uniformly distributed in thin layers next to the drain and source contacts, and in some cases from g-r traps located at the front Si/oxide interface. No different noise behavior was observed between n- and p-channel devices operating in front-gate mode. Finally, LFN comparison between FD-SOI devices of different technologies is presented for the first time, demonstrating the impact of the UTBB technology on the LFN properties.