Mr. Andersen is the husband of Mrs. Andersen and the father of Riley who all used to live in Minnesota ever since Riley was born, where he served as a coach for Riley's hockey team. When Riley turns 11, Mr. Andersen and his family move to San Francisco to start work for a tech startup company called Brang. Upon arriving in San Francisco, his work gradually consumes him and becomes more distant from his family. At home, he is usually seen talking on the phone to discuss investor problems. Due to this adjustment period, Mr. Andersen becomes oblivious to Riley's own problems and struggles. When he starts seeing an unusual new attitude from Riley, a fight results between them one night and Riley gets grounded when she talks back to her father. However, Mr. Andersen attempts to make amends later and make Riley feel better, but his words can't touch her.
One day, Riley tries to run away from home after becoming fed up with the San Francisco atmosphere. When Mr. and Mrs. Andersen learn that Riley is missing, the couple panics, searching everywhere and calling several people to find her. However, Riley returns home later that day, admitting that she misses their old home and breaks down in front of them. Bill, seeing his daughter greatly upset, comforts her and confesses that he also misses Minnesota. The three then hug together to comfort Riley.
Some time later, it is revealed that not only has he finally adjusted to San Francisco with his family but has also become highly supportive of his daughter at hockey to the point that he proudly wears the colors of Riley's team. He and Mrs. Andersen watch from the seats as Riley begins her hockey match with the opposing team.
On the day when Riley was going ice skating with friends, Jordan comes to the Andersen household to pick her up. Her parents go into a panic, fearing this could be a date. While Mrs. Andersen goes upstairs to inquire with Riley whether or not it was a date, Mr. Andersen tries to intimidate Jordan to get him to react, but the boy's mind was off in space. To pressure Jordan into revealing anything, Mr. Andersen asks Jordan what he likes to do for fun. Jordan seems to deflect, so Mr. Andersen prepares to give him "the boot". But at the last minute, Jordan admits to being in a band, causing Mr. Andersen to remember he was in a band as the lead guitarist and the two bond over the fact that they both loved AC/DC. They then listen to loud rock music while playing with air guitars. An embarrassed Riley then comes down the stairs and drags Jordan out the door. Watching their daughter go, Mr. Andersen takes the opportunity to kiss Mrs. Andersen, which only lasted for a moment.
- In Riley's First Date?, it is revealed that Mr. Andersen was the lead guitarist in a band.
- The Essential Guidebook gives his name as "Bill Anderson".