The 1981 FIA Formula One World Championship was the 35th season of FIA Formula One motor racing. It featured the 1981 Formula One World Championship for Drivers and the 1981 Formula One World Championship for Constructors, which were contested concurrently over a fifteen-race series that commenced on 15 March and ended on 17 October.

The 1981 championship was the first to be run under the FIA Formula One World Championship name. Teams were now required to lodge entries for the entire championship rather than individual races, and a standardised set of rules would be in place at every championship race, while the FIA would also set the prize money for all races. After this season, the FIA required that Formula One entrants own the intellectual rights to the chassis that they enter, and so the distinction between the terms "entrant" and "constructor", and hence also "team", have become less pronounced.

Nelson Piquet won the Drivers' Championship, claiming the first of his three drivers' titles, while Williams won the Constructors' Championship for the second consecutive year.