Working directly with 19 chief executive Simon Fuller and 19 president Robert Dodds, Scardino will be responsible for all of 19's commercial enterprises worldwide. This includes building relationships with major global brands across a variety of platforms including television, digital, mobile and live events.
Dodds said: "We have a strong commercial track record here and we work with some of the biggest brands in the world.
"Janet will be instrumental in developing these relationships and taking a strong lead in new areas. She is the most creative media person I know and will be an invaluable addition to our team."
Scardino joins 19 Entertainment after nearly a year as president and chief marketing officer with lifestage media company The Knot. She has previously worked with large media companies such as Reuters, MTV, Disney and AOL.
Scardion said: "Simon Fuller has revolutionized music, entertainment and talent management. He is a rare visionary and I am looking forward to working closely with Simon and joining the 19 Entertainment team.
"At a time when media is shifting dramatically it is critical to forge new and creative marketing models. 19's ability to create organic, brand-integrated entertainment makes it a trailblazer, and I am thrilled to lead its global commercial interests."
19 Entertainment owns entertainment brands such as 'American Idol', and all Idol derivatives over 100 countries, worth an estimated $3bn worldwide.