With this scholarship and his work selling he became a drawing & painting teacher for some Mexican states, teaching in rural schools as a cultural mission.

Howard S. Phillips, "Mexican Life Magazine" editor sent a note to Anita Brenner, in which he praised Cueva's work.

His art got excellent comments from U.S. critics, and received attention from José Juan Tablada, who may have been instrumental in getting him the commission to paint the murals in the Mexican Embassy in Washington, D.C.

In 1933 Cueva del Río began work on the Embassy frescos, with the themes: La Fiesta de las Flores y Frutas en Tehuantepec (Flowers and Fruits party in Tehuantepec), also called Fiesta Tehuana; Los Volcanes, Fraternidad Panamericana (The volcanoes and Pan-American fraternity).

"Now is among us the great Mexican painter Roberto Cueva del Río" with a deeply exaltation, pointing that: "The fresco that he is creating in the embassy will be the biggest worldwide, due the walls around the central stair has a picture continuity and ideological solution from the floor to the ceiling.

Cueva del Río makes next to José Clemente Orozco, Diego Rivera and David Alfaro Siqueiros, the quadrangle of the best paintbrush artists with real work outside of Mexico".

In 1938 he returned to Mexico where he worked for President General Lázaro Cárdenas del Río on several projects including a Mayan themes frieze for the dining room of his private home in Jiquilpan, another large mural called Historia y Paisaje de Michoacán for the dining room of his house in Pátzcuaro named Casa Eréndira (today occupied by the CREFAL).

He also completed two small panels on the traditional dance of the fish and the market in a viewpoint called Cerro Colorado or Estribo Chico in Pátzcuaro.

In 1944 he decorated the mail congress hall with a mural ”Congreso de Apatzingán.” In 1945 he was commissioned for personal portraits and created political magazine covers.