He made numerous recordings for major record labels, both in Europe and in the United States. His operatic debut was in 1898, in Linz. Foreign four years he found permanent employment at the German Theatre in Prague starting in 1905.
Specializing in Wagnerian roles, he sang at Brün from 1909 to 1911, and from 1911 until 1913 with the Vienna Volksoper while also guesting with the Vienna Imperial Opera in 1909 and the Berlin Gura Summer Opera in 1910.
In October 1913 it was announced that Leonhardt had joined the New York Metropolitan opera. Sailing from Bremen, he endured a difficult voyage before arriving in the United States. on November 6.
He first appeared on stage for his new employer in December in the role of Peter in Engelbert Humperdinck"s opera Hänsel und Gretel. Receiving critical acclaim for his work in this role, he would appear in Met productions over the course of the next nine years.
He was expected to appear in an expanded role at the met, but world circumstances would prevent this.
Beginning in December 1917 he billed himself as "Robert Leonard" to distance himself from his Germanic heritage. Nevertheless Leonhardt, a citizen of Austria, was dropped by the New York Met in April 1918 because of his status as an enemy alien despite continued critical praise. The opera"s manager, Mr.
Gatti, expressed his regret at having to make such a move.
After the war his employment recommenced with the Met and he was performing on stage again as of November 1920. Here he continued to perform until shortly before his death.
He developed an illness that lasted for some time, and never recovered. Robert Leonhardt died at Saint Mark"s Hospital in New York City on February 2, 1923.
Reviews of Leonhard"s performances are wide-ranging.
He has been noted for a "dark, steely, throaty bass" with mundane performance, although this is perhaps due to Leonhard being out of his voice"s comfort zone regarding range. Conversely, he was noted for having a "luscious and lovely Italian voice" with a splendid, spontaneous sense of humor. United States.