Dawn Lyn made her acting debut at age four in the low-budget, independent Cry Blood, Apache (1970). It wasn't until she was 12 that she discovered she had played a Native American boy in the movie. She was the original Prudence in the pilot for Nanny and the Professor (1970) TV series. By the time the pilot sold at the last minute, Dawn had already been released from her contract and cast as Dodie in My Three Sons (1960), and the producers of "Nanny and the Professor" unsuccessfully sued in an attempt to get her back. She worked steadily, financially supporting her family, until she was in her mid-teens; she says her petite stature began to work against her instead of for her, as it had when she was a child.

Dawn decided to branch out professionally, instead of concentrating on acting, and has done many things over the years, including co-owning a boutique on Pier 39 when she lived in San Francisco. People often ask her if she will act again; her answer is that while she has not actively pursued roles, that door is not closed.