After studying piano and organ 1938-43 with Lucien Jolicoeur at the Collège de Montréal, he studied 1944-7 under Alfred La Liberté (piano) and Séverin Moisse (harmony, counterpoint). He continued his studies 1947-54 at the Brussels Royal Cons with Marcel Maas (piano), André Souris (harmony), Jean Absil (counterpoint), Maurice Raskin (chamber music), and René Defossey (conducting), obtaining diplomas in these subjects. He then decided to concentrate on conducting and attended the classes of Willem van Otterloo in Hilversum, Holland, and those of Paul van Kempen at the Accademia Chigiana of Siena.
Beaudry made his debut as a conductor in 1955 on the CBC radio program 'Petit Concert'. He went on to conduct numerous concerts by the Quebec Symphony Orchestra, the MSO, the TSO, and the NACO, as well as the CBC Symphony Orchestra and the Orchestre métropolitain of Montreal. His visit to the USSR in 1957, at the invitation of the Soviet ministry of cultural affairs, was the first by a North American conductor and, as in a return visit in 1959, included appearances with several orchestras, including the Moscow SO and the Leningrad Philharmonic. He frequently conducted concerts in Europe, including some by the Czech Philharmonic Orchestra (Prague Spring Festival 1961) and others in Poland, Norway, Greece, Belgium, Switzerland, Italy, and Holland. When the MSO visited the USSR in 1962, performing for the first time abroad, Zubin Mehta and Beaudry shared the conducting duties. Beaudry conducted the orchestra in four of its Soviet appearances, as well as in one of its two concerts in Paris. He was also the first Canadian to conduct at the Paris Opera, giving a total of more than 150 performances in that theatre between 1967 and 1972, including Aida, Carmen, Don Carlos, Lucia di Lammermoor, and Tosca. Following his debut in Lucia di Lammermoor, Bernard Gavoty (Clarendon) wrote in Le Figaro (Paris, 15 Nov 1967): 'Now there's a conductor indeed! It's not a common breed. This one has bearing and presence, fine craftsmanship, dash, subtlety when required and a sense of choral balance, and he's a painstaking accompanist of soloists. I found the same Beaudry in the operatic field that I had known and enjoyed in the symphonic: poised, a perfect musician, able to command the esteem and respect of those he conducts - in short, I repeat, a conductor'.
Beaudry was guest conductor at the inauguration of the new opera house in Warsaw in 1969. Though he resided for a number of years in Paris, he returned frequently to Canada; he conducted, among other works, Verdi's La Traviata and Aida on the CBC in 1971 and Puccini's La Bohème in a production by the Opéra du Québec at the PDA and the Grand Théâtre in Quebec City in 1975. He also conducted performances given by Margot Fonteyn and Rudolph Nureyev in New York and Washington in 1974 and 1975. With the Stuttgart Opera Ballet he performed in 1973 and 1975 in New York, Washington, Philadelphia, Stuttgart, and elsewhere. Beginning in 1962, he was a guest conductor with the opera houses of Mulhouse, Lyons, Strasbourg, Nice, Toulouse, and Lille.
Beaudry conducted several works by Canadian composers, including François Morel's Esquisse (USSR 1960), Roger Matton's Mouvement symphonique No. 1 (Montreal Festivals 1961, Athens 1961, Paris 1966, Brussels 1967, Quebec City and Thetford Mines 1973), Pierre Mercure's Kaléidoscope (USSR 1957, Canada 1958, Guatemala 1959), and, Jean Vallerand's Cordes en mouvement (Paris 1972) and Le Diable dans le beffroi (Poland and Czechoslovakia 1960, Norway and Canada 1961, USSR 1962, France 1962 and 1972). He premiered some 10 works by the French composer André Casanova, including the opera Le Bonheur dans le crime, at the Théâtre du Capitole in Toulouse in 1973, a work that received the grand prix de la Création lyrique in France. The St-Jean-Baptiste Society awarded Beaudry the 1960 Prix de musique Calixa-Lavallée.