Slim was born on 28 January 1940, in Mexico City.
At the age of 11, Carlos invested in a government savings bond that taught him about the concept of compound interest.
At the age of 12, Slim made his first stock purchase, by purchasing shares in a Mexican bank.
By the age of 15, Slim had become a shareholder in Mexico's largest bank.
Slim went on to study civil engineering at the National Autonomous University of Mexico, where he also concurrently taught algebra and linear programming.
At the age of 17, Slim earned 200 pesos a week working for his father's company.
Slim graduated from college in 1961.
In 1965, profits from Slim's private investments reached US$400,000, allowing him to start the stock brokerage Inversora Bursátil.
In 1965, Slim bought Jarritos del Sur.
In 1966, worth US$40 million,Slim founded Inmobiliaria Carso.
Carlos Slim was married to Soumaya Domit in 1967.
In 1976, Slim branched out by acquiring a 60 percent share of Galas de México, a small printer of cigarette-pack labels for US$1 million
in 1980, Slim consolidated his business interests by forming Grupo Galas as the parent company of a conglomerate that had interests in industry, construction, mining, retail, food, and tobacco.
In 1981, Slim acquired a majority stake in Cigarros la Tabacelera Mexicana (Cigatam), Mexico's second largest producer and marketer of cigarettes, at a reduced price.
During the Mexican economic downturn before its recovery in 1985, Slim invested heavily.
Slim spent US$13 million to buy insurance company Seguros de México in 1984.
Established in 1986 Fundación Carlos Slim Helú sponsors the Museo Soumaya in Mexico City, named after Slim's late wife, Soumaya Domit, Opened 2011.
In 1988, Slim bought the Nacobre group of companies, which trades in copper and aluminum products, along with a chemicals business, Química Fluor, and others.
In 1990, Slim acted in concert with France Télécom and Southwestern Bell Corporation in order to buy the landline telephone company Telmex from the Mexican government, when Mexico began privatizing its national industries.
In 1991, Slim acquired Hoteles Calinda (now OSTAR Grupo Hotelero).
In 1995 Slim established Fundación Telmex, a broad-ranging philanthropic foundation, which as he announced in 2007 had been provided with an asset base of US$4 billion to establish Carso Institutes for Health, Sports and Education.
In 1996, Grupo Carso was split into three companies: Carso Global Telecom, Grupo Carso, and Invercorporación.
Slim bought the Mexican arm of Sears Roebuck in 1997.
In 1999, Slim began expanding his business interests beyond Latin America.
Soumaya Domit (Carlos`s wife) died in 1999.
Slim underwent heart surgery in 1999.
In 2000, Slim and ex-broadcaster Jacobo Zabludowsky organized the Fundación del Centro Histórico de la Ciudad de México A.C. (Mexico City Historic Center Foundation) to revitalize and rescue Mexico City's historic downtown area to enable more people to live, work and find entertainment there.
Slim has been Chair of the Council for the Restoration of the Historic Downtown of Mexico City since 2001.
Slim became a prominent figure within the American business scene by 2003 when he began purchasing large stakes in a number of major US retailers such as Barnes & Noble, OfficeMax, Office Depot, Circuit City, Borders, and CompUSA.
In 2005 Slim invested in Volaris, a Mexican airline.
On March 29, 2007, Slim surpassed American investor Warren Buffett as the world's second richest person with an estimated net worth of US$53.1 billion compared with Buffet's US$52.4 billion.
On August 8, 2007, Fortune magazine reported that Slim had overtaken Gates as the world's richest person.
In 2007, after having amassed a 50.1% stake in the Cigatam tobacco company, Slim reduced his holdings by selling a large portion of his equity to Philip Morris for US$1.1 billion.
On March 5, 2008, Forbes ranked Slim as the world's second-richest person, behind Warren Buffett and ahead of Bill Gates.
On March 11, 2009, Forbes ranked Slim as the world's third-richest person, behind Gates and Buffett and ahead of Larry Ellison.
On March 10, 2010, Forbes once again reported that Slim had overtaken Gates as the world's richest person.
Slim owns the Duke Seamans mansion, a 1901 beaux arts house on 5th Avenue in New York City, which he bought for $44 million in 2010.
In March 2011 Forbes stated that Slim had maintained his position as the wealthiest person in the world, with his fortune estimated at US$74 billion.
Slim was ranked fifth in Forbes' World's Biggest Givers in May 2011.
In 2011, Slim began buying a 70 percent stake in Geoprocesados SA's Tabasco Oil Co., gaining access to the Colombian oil market as the country seeks to boost crude and natural-gas output.
Slim has been publicly skeptical of The Giving Pledge by Bill Gates and Warren Buffett giving away at least half of their fortunes. But according to his spokesman, he devoted US$4 billion, or roughly 5%, to his Carlos Slim foundation as of 2011.
In 2011, Slim, along with the president of Mexico, Mexico City mayor, and Mexico City archbishop, inaugurated the first phase of Plaza Mariana close to Basilica de Guadalupe.
By 2012, América Movil, Slim's mobile telephone company, had taken over Telmex and made it into a privately held subsidiary.
In March 2012 Slim, along with American television host Larry King, established Ora TV, an on-demand digital television network that produces and distributes television shows.
In 2012 Slim sold the broadcast rights for the Leon games to Telemundo in the United States.
In September 2012 Slim bought 30% stakes in Pachuca and León, two Mexican soccer teams through his telecommunications company America Movil.
In December 2012, he bought all the shares of the second division team Estudiantes Tecos.
In December 2012, according to the Bloomberg Billionaires Index, Carlos Slim Helú remained the world's richest person with an estimated net worth of US$75.5 billion.
Slim and his son increased their presence in Mexico's music industry, particularly in the retail music industry since 2013.
On March 5, 2013, Forbes stated that Slim was still maintaining his first-place position as the wealthiest person in the world, with an estimated net worth of US$73 billion.
In April 2013 Slim entered the business of managing Mexican prisons to expand the investments of his construction-finance company.
In July 2013 Slim's company America Movill invested US$40 million in Shazam, a British commercial mobile phone-based music identification service for an undisclosed share of ownership.
In November 2013 Slim invested US$60 million in the Israeli startup Mobli, a company that deals with connections between people and communities corralled according to different interests.
In 2013 Slim's company, Grupo Carso opened Mexico City's Telcel Theater, which operates in conjunction with his entertainment company, Grupo CIE (Corporación Interamericana de Entretenimiento), Mexico's equivalent of Live Nation.
On April 23, 2014, Slim took control of Telekom Austria, Austria's biggest phone carrier, which has telcos in countries such as Bulgaria, Croatia and Belarus, under a 10-year agreement, was Slim's first successful business acquisition in Europe.
In May 2014 Slim opened Inbursa Aquarium, Latin America's largest aquarium.
In July 2014 Slim invested in WellAware, a Texas-based oil and gas software developer, this investment was also made with former Republican vice president Dick Cheney.
On July 15, 2014, Forbes announced that Slim had reclaimed the position of the wealthiest person in the world, with a fortune of US$79.6 billion.
In September 2014, Forbes listed Slim as number 1 on its list of billionaires with a net worth of US$81.6 billion.
Slim's stake in the Times increased again to 16.8% of the company's Class A shares on January 20, 2015 when he exercised stock options to purchase 15.9 million shares, making him the largest shareholder in the company.
In January 2015 Grupo Carso publicly launched Claro Musica, an online music service that is a Latin American equivalent of iTunes and Spotify.
In March 2015 Slim began to set his sights on Spain, purchasing Spanish real estate at rock-bottom prices within the ailing Spanish economy.
In April 2015, Slim bought the Marquette Building in Detroit and purchased PepsiCo Americas Beverages headquarters in Somers, New York for US$87 million.
On April 15, 2015, Slim formed his own oil company called Carso Oil & Gas.
On July 25, 2015, Slim's investment group Control Empresarial de Capitales invested in IMatchative, a technology startup that ranks the world's hedge funds creating in-depth behavioral profiles and business analytics.
In 2017, Slim`s net worth was reported (Forbes) to be $54.5 billion.
In 2008 Slim took a 6.4% stake valued at $27 million in the troubled New York Times Company.