The round, which raised an undisclosed amount, also saw contribution from marketing firm TEGNA and private investment firm Emil Capital Partners.
Both Sky and Emil were return backers, having invested in the firm’s US$28 million (€24 million) Series B round, which closed in January 2015.
Whistle Sports specialised in online sports-related content and claims to have now topped 170 million aggregate reach across all social channels.
“Whistle Sports has successfully captured the imaginations, attention and engagement of millennial sports fans, and consistently delivers compelling content and options to brands and agencies eager to connect with that critical and growing demographic,” said Rick Cordella, senior vice president and general manager, digital media, NBC Sports Group.
“Whistle Sports has proven to be a reliable source of original and creative content, and their data-driven approach to developing new audience insights sets them up for an even stronger future.”