The 32-year-old Argentine won his first Ballon d'Or after 2015.
The sixth award comes after the Barcelona ace scored 54 times for club and country in the 2018-19 season.
He helped Barca seal La Liga.
Here are his biggest moments from the 2018-19 season.
Messi pips Virgil van Dijk and Cristiano Ronaldo
Liverpool's Virgil van Dijk finished second. He is one of four Liverpool players in the top seven, including Sadio Mane on fourth.
Juventus and Portugal forward Cristiano Ronaldo, who has won the Ballon d'Or five times, was third in the voting.
"Today is my sixth Ballon d'Or. It's a completely different moment, lived with my family and my children," Messi said.
Messi La Liga
Messi defined La Liga season with his consistency
Messi had a superb La Liga campaign in which he amassed 36 goals and helped Barcelona become the Spanish champions, once again.
Apart from the goals, he also contributed with 13 assists. That was the joint-highest with Pablo Sarabia.
He also scored three hat-tricks in the campaign to top the charts.
His consistency helped him pip others in La Liga.
Messi delivered the goods with his astounding amount of goals
Messi and goals go hand in hand, and the season was remarkable for the senior player.
To amass 51 goals in 50 games for the club across competitions is no mean feat.
Messi has lived up to expectations every season and his tally of goals justified his talent.
Barca reached the Copa del Rey finale and the semis of the UEFA Champions League.
Messi's free-kick helped him win Goal of the Season
Messi's sublime free-kick came in a 3-0 victory over Liverpool in last season's Champions League semi-final first leg.
It was his second of the night and his 600th for the club.
He won the vote ahead of Cristiano Ronaldo.
The effort from 30 yards out against Liverpool was worthy of winning any match.
Messi proved once again he is a big match player.
Messi always delivered when needed
Messi carried Barcelona like he does every season and made sure they they managed to reach the latter stages of competitions.
Barca's vulnerabilities meant that they couldn't win the UCL or the Copa del Rey, however, when it came to the big matches, Messi always delivered.
He was also the top goal-scorer in the Champions League (12) to show his mettle.
Messi fought mental challenges to rise high
Messi suffered a heartbreak during the FIFA World Cup 2018. He scored just one goal for Argentina and couldn't carry his nation. However, he overcame this and delivered for his club. His performance, this term, proved why he is one of the GOATs.