Hefner's key role in reaching the group's fund-raising goal was announced by Los Angeles city officials, and the San Francisco-based Trust for Public Land at a news conference in the .
The land trust needed to collect a total of $12.5 million by this Friday under a deal with a group of Chicago investors who bought the 1,820-foot (555-meter) ridge, called , from the estate of billionaire Howard Hughes in 2002.
The trust will now purchase the 138-acre (56-hectare) adjacent parcel and turn it over to the city to be incorporated into the surrounding Griffith Park, preventing any construction that would mar the postcard-perfect view of the Hollywood sign nearby.
"My childhood dreams and fantasies came from the movies, and the images created in Hollywood had a major influence on my life and Playboy," Hefner said in a statement. "As I've said before, the Hollywood sign is Hollywood's Eiffel Tower and I'm pleased to help preserve such an important cultural landmark."
Other private donors to the Hollywood sign preservation effort included actor Tom Hanks and director Steven Spielberg, the land trust said.