It happened at Finch and Sparrow Games in Signal Hill on Friday at around 6:30 p.m.
The owner told Eyewitness News the man came in and asked to see the Beta: Black Lotus card from the game "Magic: The Gathering" - a popular tabletop and digital collectible card game.
He then walked away with the card, ran out the door and jumped into a getaway car that was waiting down the street.
The owner said the Beta: Black Lotus card is known as the most iconic card in the game and said the one the suspect stole was signed by the creator of the game and the artist of the card.
Meanwhile, the suspect was caught on surveillance video.
Anyone with information is urged to contact police.