The accolade seals Messi's status as the greatest player of his generation after he saw off Real Madrid rival Cristiano Ronaldo and Barcelona team-mate Andres Iniesta for the prize.
Messi received a vote share of 41.60 percent to 23.68 for Ronaldo and 10.91 for Iniesta.
VIDEO: Lionel Messi wins his fourth Ballon d'Or award
Messi and former French star, UEFA president Michel Platini, had prior to Monday been the only players to win three straight Ballon d'Or awards while Dutch greats Johan Cruyff and Marco Van Basten both won the accolade on three occasions.
Spain's Vicente del Bosque was named coach of the year for 2012, seeing off competition from Real Madrid's Jose Mourinho and former Barcelona coach Josep Guardiola.
Messi's success crowned another landmark year for the Argentine who is already the top scorer in La Liga for the ongoing season with 25 goals, having also broken Gerd Mueller's 40-year record for the most goals in a calendar year.
He finished 2012 with an astonishing 91 goals in all competitions.
But Messi has insisted his scoring records will mean nothing if Barcelona do not go on to take the La Liga title off Real or fail to win the Champions League.
"It is incredible to receive this prize once again and it's impressive it makes it four in a row. I would like to share this with my Barca team-mates - particularly with Andres, who is here with me," said the ever unassuming Messi.
"I am proud to be able to train alongside him every day. I am also thinking of my team-mates in the Argentina squad," he went on.
"Thank you to all those who voted for me, skippers, coaches and national coaches.
"Thank you too to my family, my friends and of course my wife and son, who is the best thing that ever happened to me," said the 25-year-old from Rosario, who in November became a father to son Thiago.
Beforehand he had said winning for Barcelona outweighed any personal glory.
"It's nice to beat records but the win for the team is what is important. My goals are to win titles with the team, the Spanish league, Spanish Cup or Champions League is more important than any personal records."
Barca coach Tito Vilanova had already eulogised his player in advance of Messi's win.
"Leo's great quality is that he plays as if he is still a child," Vilanova opined.
"He was always good as a youngster and you didn't need to be a coach to say that. It was a joy to see him play as a 15-year-old and that continues now."
Portugal captain Ronaldo at least has the consolation of having won in 2008 before Messi's hegemony began while Iniesta can for his part bask in the knowledge that he has won a World Cup and two Euros - including Euro 2012 - whereas Messi still has to replicate such achievements at international level.
Until he can lift top honours with Argentina, some observers will insist he cannot be classed as the greatest player ever, moving ahead of Pele and Diego Maradona.
List of football award winners for 2012 after a ceremony at FIFA headquarters in Zurich on Monday:
Ballon d'Or:
1. Lionel Messi (ARG)
2. Cristiano Ronaldo (POR)
3. Andres Iniesta (ESP)
Coach:
1. Vicente Del Bosque (ESP)
2. Jose Mourinho (POR)
3. Pep Guardiola (ESP)
Team:
Iker Casillas (ESP), Dani Alves (BRA), Gerard Pique (ESP), Sergio Ramos (ESP), Marcelo (BRA), Xabi Alonso (ESP), Xavi Hernandez (ESP), Andres Iniesta (ESP), Lionel Messi (ARG), Radamel Falcao (COL), Cristiano Ronaldo (POR)
Best goal:
1. Miroslav Stoch (SVK)
2. Falcao (COL)
3. Neymar (BRA)
Fairplay:
Uzbekistan Football Federation (UFF)
FIFA president award:
Franz Beckenbauer (GER)
Woman player:
1. Abby Wambach (USA)
2. Marta (BRA)
3. Alex Morgan (USA)
Woman team coach:
Pia Sundhage (USA/SWE)