Two hours after the Oilers won the Stanley Cup in 1988, Gretzky learned from his father that the Oilers were planning to deal him to another team.^]Walter had known for months, but kept it from Gretzky so as not to upset him. According to Walter, Gretzky was being "shopped" to Los Angeles, Detroit, and Vancouver. According to Gretzky, Pocklington needed money as his other business ventures were not doing well, and had gone "sour" on Gretzky and wanted to move him. At first, Gretzky did not want to leave Edmonton whatsoever, but he later received a call from Los Angeles Kings owner Bruce McNall while on his honeymoon asking permission to meet and discuss the deal. During the meeting, a chance phone call from Pocklington to McNall occurred, without Pocklington's knowledge that Gretzky was in the room. Gretzky listened in as Pocklington summarily expressed his desire to be rid of Gretzky, a moment that swung momentum completely in McNall's favor. Angered and hurt by Pocklington's comments, Gretzky informed McNall that his prerequisites for a deal to take place were that Marty McSorley and Mike Krushelnyski join him as teammates in Los Angeles. After the details of the trade were finalized by McNall and Pocklington, one final condition had to be met: Gretzky had to call Pocklington and request a trade. When Pocklington told Oilers general manager and head coach Glen Sather about his plans to trade Gretzky to L.A., Sather tried to stop the deal, but when he found out that Gretzky had been involved in the negotiations, he changed his attitude and requested Luc Robitaille in exchange. The Kings refused, instead offering Jimmy Carson.

On August 9, 1988, in a move that heralded significant change in the NHL, the Oilers traded Gretzky, along with McSorley and Krushelnyski, to the Kings for Carson, Martin Gelinas, $15 million in cash, and the Kings' first-round draft picks in 1989 (later traded to the New Jersey Devils – New Jersey selected Jason Miller), 1991 (Martin Rucinsky), and 1993 (Nick Stajduhar)."The Trade", as it came to be known, upset Canadians to the extent that New Democratic Party House Leader Nelson Riis demanded that the government block it, and Pocklington was burned in effigy outside the Northlands Coliseum. Gretzky himself was considered a "traitor" by some Canadians for turning his back on his adopted hometown, and his home country; his motivation was widely rumoured to be the furtherance of his wife's acting career.

In Gretzky's first appearance in Edmonton after the trade—a game that was nationally televised in Canada—he received a four-minute standing ovation. The arena was sold out, and the attendance of 17,503 was the Oilers' biggest crowd ever to that date. Large cheers erupted for his first shift, his first touch of the puck, his two assists, and for Mark Messier's body check of Gretzky into the boards. After the game, Gretzky took the opportunity to confirm his patriotism: "I'm still proud to be a Canadian. I didn't desert my country. I moved because I was traded and that's where my job is. But I'm Canadian to the core. I hope Canadians understand that." After the 1988–89 season, a life-sized bronze statue of Gretzky was erected outside the Northlands Coliseum, holding the Stanley Cup over his head.

The Kings named Gretzky their alternate captain. He made an immediate impact on the ice, scoring on his first shot on goal in the first regular-season game. The Kings got off to their best start ever, winning four straight on their way to qualifying for the playoffs. Despite being underdogs against the defending Stanley Cup Champion Edmonton Oilers in the Smythe Division semifinals, Gretzky led the Kings to a shocking upset of his old squad, spearheading the Kings' return from a 3–1 series deficit to win the series 4–3. He was nervous that Edmonton would greet him with boos, but they were eagerly waiting for him. For only the second time in his NHL career, Gretzky finished second in scoring, but narrowly beat out Pittsburgh's Mario Lemieux (who scored 199 points) for the Hart Trophy as MVP. In 1990, the Associated Press named him Male Athlete of the Decade.

Gretzky's first season in Los Angeles saw a marked increase in attendance and fan interest in a city not previously known for following hockey. The Kings now boasted of numerous sellouts. Many credit Gretzky's arrival with putting non-traditional U.S. hockey markets on "the NHL map"; not only did California receive two more NHL franchises (the Mighty Ducks of Anaheim and San Jose Sharks) during Gretzky's tenure in L.A., but his popularity inSouthern California proved to be an impetus in the league establishing teams in other parts of the U.S. Sun Belt.

Gretzky was sidelined for much of the 1992–93 regular season with an upper back injury, the only year in which he did not lead his team in scoring. However, he performed very well in the playoffs, notably when he scored a hat trick in game seven of the Campbell Conference Finals against the Toronto Maple Leafs. This victory propelled the Kings into the Stanley Cup Finals for the first time in franchise history, where they faced the Montreal Canadiens. After winning the first game of the series by a score of 4–1, the team lost the next three games in overtime, and then fell 4–1 in the deciding fifth game where Gretzky failed to get a shot on net.

The next season, Gretzky broke Gordie Howe's career goal-scoring record and won the scoring title,^[32] but the team began a long slide, and despite numerous player and coaching moves, they failed to qualify for the playoffs again until 1998. Long before then, running out of time and looking for a team with which he could win again, Gretzky had been traded from the Kings at his request.

CBC Sports - The Wayne Gretzky Trade: Behind the Scenes 

TSN Video - The Trade : I Promised Messe Trade: ''I

Pomised Mess''