As director of brand marketing, communications and fundraising at the first aid charity, Conway will help increase awareness of its work among the public and boost its income from fundraising.
Conway, who has 20 years' experience across brand management, marketing and comms for brands such as Kraft, Danone and the BBC, will report to St John Ambulance CEO Sue Killen.
Commenting on the move, Conway said: "I am delighted to be joining St John Ambulance and a brand that has such enormous heritage and affection among the British public.
"I look forward to helping accelerate our growth as the nation’s leading first aid charity and in particular ensuring that more lives are saved each year by increasing the awareness of first aid."
Conway joined YouView in April 2012 ahead of the brand’s launch in July of the same year and was responsible for all its marketing and PR activity.
It is unclear whether Conway has been replaced at YouView, which was unavailable for comment at the time of publication.
At St John Ambulance Conway fills the role vacated by Scott Jacobson who departed in July amid a major restructure of the charity.
UPDATE: YouView PR manager Victoria Fairclough confirmed that recruitment for a replacement was currently underway.