López Obrador, a member of the National Regeneration Movement (MORENA) and former Head of Government of the Federal District, had previously run for president in the 2006 and 2012 elections.

Following his victory, on 2 July, López Obrador announced his transition team, comprising Alfonso Romo and Carlos Manuel Urzúa Macías for the economy; Héctor Vasconcelos and Marcelo Ebrard for foreign relations; Julio Scherer Ibarra [es], Olga Sánchez Cordero, and Tatiana Clouthier for domestic affairs; and César Yáñez Centeno Cabrera [es] for communications.

[8] On 3 July, he met incumbent president Enrique Peña Nieto at the National Palace,[9] where they spoke on the North American Free Trade Agreement (NAFTA), the construction of the New International Airport for Mexico City (NAICM), energy reform, the budget, and security.

[9] Once his victory was certified by the Federal Electoral Tribunal, López Obrador once again met with Peña Nieto on 9 August to formally begin the transition process.

[13] From 22 to 25 October, he held a nationwide referendum on whether or not the New International Airport for Mexico City was to be scrapped, citing that the project was rife with graft and a waste of taxpayer money.

[15] During the transition period, López Obrador and his team held meetings with Peña Nieto’s cabinet,[16] as well as with the Consejo Coordinador Empresarial [es] (CCE),[17] the National Governors Conference (CONAGO),[18] and presidential candidates José Antonio Meade and Ricardo Anaya.

López Obrador was the first president to address Congress since the year 2000, following the brief inaugurations of Felipe Calderón and Enrique Peña Nieto, who had only taken the oath and then left.

A rally in support of López Obrador took place in the Zócalo of Mexico City, where representatives from 68 indigenous groups presented him with the bastón de mando, a traditional ceremonial staff.

This symbolic gesture marked the first time a Mexican president had received the staff, signifying the recognition of López Obrador as a leader by the indigenous groups.

[31][32] The proposed cabinet remained mostly unchanged, with the exception of Héctor Vasconcelos, was initially chosen to serve as Secretary of Foreign Affairs but was later replaced by Marcelo Ebrard.

His policies aimed to reduce reliance on imports, strengthen state-run companies like Pemex and the CFE, and stimulate growth and employment through large-scale infrastructure projects.

[51][52] These challenges included the excessive growth of public debt under the previous administration, conflicts with economic actors, the China–United States trade war, and Donald Trump's tariff policies.

Some setbacks were self-inflicted, such as the cancellation of the Mexico City Texcoco Airport and reduced spending due to his austerity measures, which brought down construction investment.

López Obrador's commitment to austerity, even amidst the crisis, helped maintain a low budget deficit and public debt,[55] earning him a reputation as a fiscal hawk.

[60][61] Upon entering office, López Obrador implemented his proposed "Republican Austerity," which aimed to reduce spending on political privileges and non-essential government products and services.

To attract and retain foreign investment, particularly from the United States, taxes were reduced in northern border areas, promoting economic expansion in these regions.

In December 2018, López Obrador ordered the creation of a truth commission to re-examine one of the country's most notorious unsolved crimes: the kidnapping and presumed murder of 43 trainee teachers who disappeared after they were attacked by cartel gunmen and corrupt police officers.

[80] On 1 March 2019, López Obrador said that he would open up the General National Archives to show how intelligence agencies, particularly the CISEN, targeted activists and opposition groups during the Dirty War.

In keeping with this promise, he released a plan to create a Mexican National Guard under control of the military and the Secretariat of Security and Civilian Protection (which was itself established by López Obrador) and would be in charge of "preventing and combating crime".

[85] By early 2020, López Obrador restored the Naval Infantry Corps' role in fighting drug cartels,[86] and he relied on the military for tasks such as law enforcement and construction.

President López Obrador pointed out that contrary to his proposed plan, past approaches failed because they were based on a misunderstanding of the core problem, which according to him, is the country's social disparities that resulted from economic policies of past presidencies in the years prior that caused the drug problem in the first place which in turn have turned the country into a hotbed of the illegal drug trade globally.

[104] López Obrador noted the enormous importance of the natural resource for the rechargeable battery industry and plans to cooperate with Bolivia and Peru in the technological sphere, as well as to adopt the Bolivian model of lithium mining, wherein companies have to commit to establish a complete value creation chain.

[109] Despite this, in his first year, he had hosted multiple foreign leaders in Mexico City, including Pedro Sánchez of Spain in January[110] and Miguel Diaz Canel of Cuba[111][112] and Carlos Alvarado Quesada of Costa Rica[113] in October.

[114] López Obrador justified his actions in a press conference the following day, taking the position alongside other governments such as Cuba, Venezuela, and Argentina that Morales was the victim of a political coup d'état.

[117] Days later, Bolivia deployed a large number of security forces outside the embassy and ambassador's residence in La Paz, and the Mexican government claimed they were intimidating, harassing, and photographing diplomats.