He was born in the city of Comayagüela, Honduras. His wife, Bessie Watson, was an American citizen with whom he had two daughters. He completed university studies in the National Autonomous University of Honduras where he earned a bachelor's degree in Juridical and Social Sciences. Later, Reina continued his postgraduate studies in the cities of London and Paris.
Throughout his long political career Reina held a number of political governmental and international jobs, including judge in the court of Tegucigalpa, peace member of the international court of The Hague, Ambassador of Honduras to France, and president of the Central Executive Council (CCE) of the Liberal Party, among other important positions.
Reina was arrested several times for his political activities in opposition to the military governments during his younger years. The first time was in 1944 for protesting against dictator Tiburcio Carías. Later in the 1960s he was sent to prison twice by General Oswaldo López, who had taken over the Honduran government through the use of military force. This led Reina to become a fierce defender of human rights throughout the rest of his life. In 1979 he was nominated president of the Inter-American Court of Human Rights of the Organization of American States.
Carlos Reina became president in November 1993, with the Liberal Party of Honduras (PLH, Partido liberal de Honduras), after defeating Oswaldo Ramos, the candidate of the National Party of Honduras with 56% of the vote. He was accompanied by his vice presidential candidate: retired General Walter López, the politician Juan de la Cruz Avelar and the lady Guadalupe Jerezano Mejía.
On January 27, 1994 Reina replaced president Rafael Leonardo Callejas. Reina inherited a relatively difficult economic situation from the existing nationalist administration. Foreign debt weighed heavily on the economy of the country: debt service represented 40% of Honduran exports. Even though approximately 700 million dollars were condoned to Honduras, the debt 'was' still higher than that it had been at the beginnings of 1990.
In his first presidential speech Reina launched his moral revolution: " I pledge my word of honor before God, before the people and before history, that we will go forward in this enterprise that we have imposed upon ourselves. We will defeat corruption; we will give currency to social liberalism. We will see the moral revolution to its end." The issue of whether his plan was a success or a failure is still highly controversial.
One of Carlos Roberto Reina's main objectives during his government was the reform of the Armed Forces. His reforms were mostly realized by the end of his first year in office. The first one was the total transfer of all power in hands of military men to civilian authorities, followed by the abolition of compulsory military service in the country. These and other reforms to the military are also controversial to the ruling elites, they believed it fomented gangs, by eliminating a source of employment and education for young men.
Carlos Roberto Reina finished his presidency on January 27, 1998. Later, in October 1998, Reina began his period as president of the Central American Parliament (Parlacén), where he remained until October 28, 1999. Finally on August 19, 2003, Carlos Roberto Reina committed suicide from a gunshot at the age of 77. His brother revealed that Reina was suffering from health issues relating to the gallbladder and pancreas.