She is portrayed by Candace Moon.
Laura was a kind woman who loved her son dearly and wanted the best for him. Much like Daniel LaRusso, Johnny would have been raised by a single mother had Laura not married Sid Weinberg, a wealthy yet inconsiderate businessman who clearly was only interested in her looks. Sid treated her son very poorly, but Laura deemed it important that Johnny grow up with more than she could give him alone. Laura was protective of her son and often stuck up for him whenever Sid berated him for his interests. Sid's churlish ways affected a young Johnny who turned to the head sensei of the Cobra Kai Dojo, John Kreese for guidance.
After losing Ali, Laura ultimately became Johnny's sole source of love and support. Though it's unknown how their relationship change in years that Johnny grew older and his life went further downhill
Evidently, Laura had been the glue that held the family together. When she died, the family disintegrated as only Johnny and Sid were left, and the relationship of both men turned to nasty hatred. Sid also grew to detest Johnny even more, as prior to her death she made Sid promise he will watch out for Johnny.
Johnny, in turn, had been devastated by the loss of his mother, in particular that he had gotten his wife, Shannon, pregnant with their only child, and Laura died prior to the baby's due date. Although Johnny's decision to be a father was unrelated to his mother's passing, Johnny attacked himself for not giving Laura the chance to experience life as a grandmother and be there to see Robby's birth.
Iis apparent that Johnny loved his mother very much, as he keeps a framed photo of her in his living room alongside a picture of a younger Robby, and looks at both often.
Laura first appears in the first episode of Cobra Kai, "Ace Degenerate". She is seen in a photo and briefly mentioned by Sid. Laura makes her first actual appearance in a flashback in the sixth episode, "Quiver", where she argues with Sid about Johnny taking Karate classes when Sid berates him for his interest in the topic. Even if she spoiled him a little bit, she provided some much needed love, understanding and encouragement to her son. She also did her best to protect Johnny from his abusive and uncaring stepdad. Johnny is seen cleaning off her photo and looking at it in his apartment in the eighth episode, "Molting".