Local media reported that police were treating the incident as minor trespass and were investigating.
The sign on Mount Lee is made of 45-foot (13.7m) tall letters.
Voters in California approved the legalisation of marijuana in a ballot held at the same time as the presidential election - on 8 November.
The prank has not caused lasting damage to the sign, however, as parts of both "O" letters were covered by tarpaulins to make them look like a lower-case letter "E".
The Los Angeles Times reports that a single person was recorded on security cameras climbing the sign to hang the materials.
A similar prank took place in 1976, to mark a relaxation in the state's marijuana laws.
Residents of Los Angeles' most famous neighbourhood woke up on New Year's Day to find the world-famous Hollywood sign had been changed to read "Hollyweed".