Officers responded to reports of the mountain lion sighting on Friday at a plant nursery south of State Route 118, CDFW officials said.
When officers tranquilized it, they discovered a tag identifying the male cat as one of three kittens born to mountain lion P-39, who was fatally struck by a car in December.
Two of the three kittens were also later killed by vehicles, and the whereabouts of the third kitten, P-50, were unknown until now.
Wildlife officers examined the young guy and said he's healthy.
They moved P-50 to the Santa Monica Mountains and after he woke up from the tranquilizer, officers said he walked away on his own.