Due to be shown during the closing ceremonies for the Beijing Olympics on Sunday, the ad shows Deborah Phelps thanking her champion swimmer son in what will be the final instalment of Johnson's 'Thanks, Mom' series.
Other Olympic athletes who have appeared in the ads thanking their mums include swimmer Cullen Jones and gymnast Beth Tweddle.
Deborah Phelps says that while the world looks to Michael as an Olympic champion, to her he's still a little boy even if he is 6'4" and eats 12,000 calories a day.
Fred Tewell, group product director at Johnson's, a brand owned by Johnson & Johnson, said the company saw Phelps in the crowd watching her son swim and exhibiting the "nurturing and caring" virtues Johnson is all about.
Phelps, a head teacher, is now the baby care line's 'Official mum of the Olympic Games'.
The company has refused to reveal how much if at all the swimmer's mother has been paid for her endorsement, but it says it is donating a sum in her name to a group of children's charities and earthquake relief projects around the world.
Johnson & Johnson is an official sponsor of the Beijing Games, at an estimated cost of £50m in cash and merchandise donations.
Other official sponsors include Adidas and China Mobile.