He was ordained on 18 March 1961 by Francisco Panal Ramírez OFM, bishop of La Vega. He served as Vicar cooperator of the cathedral of La Vega, 1961–1963. Further studies in Rome, 1963–1965. Chancellor and secretary of the diocesan curia of La Vega, 1966–1968. Further studies, Rome, 1968–1969. In the diocese of La Vega, 1969–1978, diocesan assessor for the pastoral of the youth and pastor of the cathedral, 1969–1970. Vicar for the pastoral and pro-vicar general, 1970–1976. Vicar general, 1976–1978. At the Pontifical University of St. Thomas Aquinas Angelicum he earned a licentiate in social science in 1965. Besides his native Spanish, he speaks Italian, English, German, Portuguese and Latin.
López Rodríguez organized a meeting of the Latin American bishops held in Santo Domingo in 1992, which was a showcase for his very traditional views, described as "temporalist and pyramidal" by veteran Vatican observer Giancarlo Zizola. He tends to support the integralist view that the organic relationship of social classes supersedes social differentiation and social conflicts. He has advocated adding the Catholic feast of the Annunciation, 25 March, to the national holidays celebrated in the Dominican Republic.
Recall of nuncio accused of sexual abuse
In July 2013, López Rodríguez reported to Pope Francis personally that the papal nuncio to the Dominican Republic was rumored to have engaged in the sexual abuse of minors, which resulted in the nuncio's recall. He continued for several weeks to praise the nuncio, Józef Wesołowski, in public and say that his recall was routine. By the second week of September he asked the civil authorities to investigate the matter with "determination".
Homosexuality
During a 27 June 2013 interview, responding to a question about Barack Obama's appointment of Wally Brewster, an openly gay man, as U.S. ambassador to the Dominican Republic, Lopez Rodriguez expressed his opposition to the appointment of a homosexual ambassador and said it was an attempt to promote the approval of same-sex marriages in the D.R. Moments later, when asked about problems between Haiti and the D.R. resulting from Haiti's claim that bird flu could be found in the D.R., Cardinal López Rodríguez laughed and said: "After talking about faggots and lesbians, now we'll talk about chickens". In the Dominican Republic, the wordpájaro is used to refer pejoratively to a male homosexual. In June 2014, after Brewster and his husband released a video promoting the celebration of June as Gay Pride Month, Lopez Rodriguez said "Diplomacy is not for that sort of thing, an absolutely negative propaganda" and that Brewster should “take his gay pride elsewhere". In December 2015, a week after Brewster criticized corruption in the Dominican Republic, Lopez Rodriguez said "That man needs to go back to his embassy. Let him focus on housework, since he's the wife to a man." These remarks were criticised by the US State Department. US Senator Dick Durbin asked Pope Francis to ask Rodriguez to treat Brewster with respect, citing the Pope's comments on the need to respect the dignity of all.