The general public is welcomed starting May 21, but reservations are required and only open to California residents.
Tim Withers, of Huntington Beach, was the first person to walk through the gates on Thursday.
"It's just amazing to be back at the park, reopen again with the rides and we're all just very excited," he said.
Those over the age of 2 are expected to wear their masks when they're not seated to eat. Guests will also need to follow COVID-19 safety protocols, like waving to characters from a distance.
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The timing couldn't be better since the park is celebrating its 100th anniversary. Visitors will be treated to the new Knott's Bear-y Tales: Return to the Fair 4-D interactive dark ride. The story is a continuation of the Bear-y Tales ride and welcomes back the Bear family and Crafty Coyote.
"The Bear family has always been making pies, and the comic villain, Crafty Coyote, is back. This time he has some pups. So everyone has grown a little older," said Ken Parks, the theme park's vice president of entertainment.
Visitors can expect markers to enforce physical distancing while waiting for rides.
Guests will also be able to enjoy the annual Knott's Summer Nights event starting May 21 through Sept. 6.
The amusement park had been closed through the pandemic, except for special outdoor events.