The 28-year-old Venezuelan attacker has joined the Magpies on a season-long loan from the Hawthorns residents, with Dwight Gayle going the other way as part of the deal.
"Newcastle United are delighted to confirm the signing of striker Salomon Rondon on a season-long loan from West Bromwich Albion," the Toon announced via their official website on Monday.
"As part of the deal to secure Rafa Benítez's number one transfer target, Dwight Gayle moves in the opposite direction and will remain on loan with the Baggies for their 2018/19 Championship campaign."
Rondon joined the Baggies from Russian outfit Zenit Saint Petersburg in 2015 but will be playing his football with Rafa Benitez's side next season.
"It's an honour to be here and I'm excited to get started with my teammates," the forward told the club's website. "The clubs were talking for a long time and now I'm focused on the season to help my teammates to get the points to do well this season.
"It's one of the biggest clubs in the Premier League and I knew about the interest of the gaffer, so I'm happy to be here."
"I am delighted to sign Salomon," Benitez added. "When we were looking for options up front, we knew how important experience would be. Salomón has been in the Premier League for a while and he knows how demanding it is."
Gayle, meanwhile, has also left on a loan deal, having signed for the Magpies from Crystal Palace two summers ago. And he claims he's "buzzing" to get started under Darren Moore.
“The manager attracted me," the 27-year-old declared. "He’s really enthusiastic about my game and I’m buzzing to come down and I can’t wait to get started."