The Scotland international midfielder, 26, made 42 appearances for the Cherries last season as they stayed up in their debut Premier League campaign.
Newcastle were relegated but new Magpies boss Rafael Benitez has signed Gent keeper Matz Sels and is chasing Crystal Palace forward Dwight Gayle.
Ritchie joined Bournemouth from Swindon Town for £500,000 in 2013.
Bournemouth's Matt Ritchie is to have a medical before a proposed £12m move to Newcastle, reports BBC Solent Sport.