The 22-year-old five-time Paralympic swimming champion from Aldridge, Walsall, has signed up to be an ambassador for the insurance company which encourages people to improve their personal health by providing them rewards and incentives to keep motivated.
Simmonds joins other sporting heroes who promote Vitality in the same role including former Olympic Heptathlon gold winner Jessica Ennis-Hill, English rugby union star Maro Itoje, English cricket captain Joe Root and former Rugby World Cup champion Jonny Wilkinson.
The British swimmer has taken on the voluntary position indefinitely and will attend upcoming events to help promote Vitality.
She said: "I’m proud to be joining Vitality as an ambassador.
"Health and wellbeing is really important to me and I’m looking forward to helping and inspiring others to make positive lifestyle changes.
"I truly believe everyone should have the opportunity to live a healthier and happier life so I’m excited to work with Vitality alongside the other influential sporting ambassadors."
Vitality CEO Neville Koopowitz added: "We are delighted to welcome Ellie as an Ambassador.
"Ellie is an incredible young talent and already inspires many with her determination and focus.
"We look forward to working with her and sharing our collective passion for healthy living."
Earlier this month Simmonds announced she was backing Children in Need's latest fundraiser.
She urged people to 'do their thing' to support the annual campaign whether it was wearing fancy dress for a day or running a marathon.
Ellie, who went to Cooper and Jordan School and the Aldridge School, shot to fame in 2008 when she won two gold medals for Great Britain, despite being 13-year-old and the youngest member of the team.