The Ireland international, who was born in Huddersfield, made his last appearance for Warrington as a substitute in last Saturday’s Betfred Super League Grand Final loss to Wigan Warriors.
He was also on the bench for Warrington’s Ladbrokes Challenge Cup final defeat by Catalans Dragons two months ago.
King, 23, made his debut in 2014 and went on to play 97 times for Warrington, scoring seven tries. He also had loan spells at North Wales Crusaders and Rochdale Hornets.
He will begin training with Wakefield in November and said: “I am really excited.
“Chris Chester [Trinity’s coach] came to speak to me during the season and sold me the vision for the club and the direction of where Wakefield is going.
“I am really looking forward to it and being able to meet the rest of the lads in pre-season.”
Chester predicted: “George will add some real toughness to what already is a big pack. He will bring plenty of energy to the group and I am really pleased he has chosen to sign for Wakefield for the next couple of seasons.
“I look forward to working with him and seeing what he can bring to the side.”