Twenty years after his World Cup debut and a career that lifted him above Pelé and Diego Maradona as soccer's greatest player, at 39 he could not will Argentina to become the first repeat champion in more than a half-century.
Spain outplayed the Albiceleste from the opening whistle at MetLife Stadium in New Jersey, where the overwhelming majority of 80,663 were hoping for a recoronation.
Ferran Torres scored 37 seconds into the second extra-time period on Sunday (Monday AEST), lifting Spain to a 1-0 victory and their second World Cup title.
Instead of Messi becoming a two-time champion, the crown passed. He fought back tears and had a look of misery as he and teammates faced applauding and bowing Argentina fans at the stadium's south end while Spanish stars lifted the trophy on a podium at the centre stripe.
After leading Argentina to victory in the 2022 final against France, sandwiched between consecutive Copa America championships, Messi could only bow his head, grimace and put hands on hips as Spain's Lamine Yamal, less than a week past his 19th birthday and projected as the sport's next big thing, ran to embrace Torres after the goal.
"I hope that everyone feels proud of him, of what he's achieved because he's the best football player ever stepping foot on a pitch," Argentina coach Lionel Scaloni said of Messi.
Spain's dominance was thorough in the final and throughout the World Cup as they extended their unbeaten streak to 38 games, the longest by a European team.
When Messi left European soccer for MLS three years ago after four Champions League medals and 12 league titles with Barcelona and Paris Saint-Germain, some speculated he would be another retiree moving to Florida.
Instead, he led Argentina back to the final with eight goals and four assists and boosted his World Cup career total to 21 goals, the record until France's Kylian Mbappé scored twice in Saturday's third-place game to surpass him to 22.
Messi became the first player to start three World Cup finals and raised his international goals total to 125, second only to Cristiano Ronaldo's 146. He is now regularly mentioned in the same breath as Maradona and Pelé, himself a three-time World Cup champion.
With his distinctive slow walk, arms swinging at his side as he waited for the right moment to burst into a sprint, the diminutive 5-foot-7 attacker was the centre of attention any time he got the ball on the right flank. Opponents and fans waited for him to cut to the center and unleash a shot with his lethal left foot.
"The first idea was to keep Messi at bay," Spain coach Luis de la Fuente said.
Half a dozen Spanish players walked over to Messi after the final whistle to hug and console him. Messi dropped to the grass, hands behind him, staring.
When Spain later formed a guard of honour for Argentina players to approach the podium for their second-place medals, Messi tried to smile but couldn't. He had a blank look as he walked through and a few opponents patted him on the back and chest.