Reátegui graduated from the University of the Pacific with a licence in economics, in 1987. In 1991, he opened his own drugstore in Tarapoto, which he still owns and manages and which has developed into a chain of supermarkets since 1998. Moreover, he manages a farm in Peruvian High Amazonia. From 1994 to 1995, he was the president of the chamber of commerce.
From 1994 to 2000, Reátegui was the provincial chairman of the political movement IDEAS. In 1995, he was elected to be mayor (alcalde of the San Martín Region for a three-year term. From 1997 to 2000, he was national secretary-general of the Vamos Vecino party, close to authoritarian president Alberto Fujimori. In 2000, he was elected to the Congress to represent his region and the fujimorist Peru 2000 alliance, however the Congress was dissolved early in 2001 due to Fujimori's resignation. In 2006, he was re-elected, this time on the Alliance for the Future list. He was elected for another five-year term, in 2011, now sitting with the Fuerza 2011 party.