The 25-year-old began his senior career in non-league football and moved to Selhurst Park from Peterborough in summer 2013, following spells with Stansted FC and Dagenham and Redbridge.
The one-time Arsenal academy player bagged 25 goals in 75 appearances for the Eagles across all competitions, including 15 strikes during three campaigns in the Premier League.
But Gayle managed just 15 Premier League appearances last season – the fewest since signing for Palace three years ago – and had been tipped to leave the club in the build-up to the summer window.
It was revealed earlier this week that the Walthamstow-born striker had flown to Tyneside for a medical and Newcastle have now confirmed his arrival via their official website.
Gayle has signed a five-year contract with the Championship outfit, who Sky Sports claim paid £10million for his services.
Upon putting pen to paper, Gayle said; “It’s a dream come true to be at a big club like this.Newcastle has a massive fan base and a great history so it is amazing to be here.
“I can’t wait to get started, prove myself and score the goals that take us back up to the Premier League. It’s where this Club belongs.”