All Mercedes-powered cars were originally due to take a new spec of MGU-K for next weekend's second Silverstone race, which will be the fifth round of the 2020 world championship.
The new spec has been developed specifically to address potential reliability concerns after running on track and the Brixworth dyno this year.
However, the team has decided to give Hamilton his new unit one race early, after some potential "anomalies" emerged following the Hungarian GP.
His teammate Valtteri Bottas and the cars of Racing Point and Williams will take theirs at the 70th Anniversary race.
Drivers are allowed three for the season, although deciding when to allocate them has been complicated in 2020 by the uncertainty of how many races will ultimately take place.
A team spokesman told Motorsport.com: "It's a precautionary change one race earlier than planned due to some data anomalies after Hungary. It's an updated spec of MGU-K for reliability reasons, which will be on all cars from next weekend."
Hamilton becomes only the fifth driver to take extra PU elements during the 2020 season, following Pierre Gasly (V6, turbo, MGU-H, MGU-K, electronics), George Russell (V6, turbo, MGU-H), Kevin Magnussen (energy store, electronics), Alex Albon (electronics) and Antonio Giovinazzi (electronics).