First recorded by Harry Richman (US #1 1930).
Other hit versions by Leo Reisman & His Orchestra (US #20 1930), Clark Gable (1939), Fred Astaire (1946), Ella Fitzgerald (1958), Taco (US #4/CAN #5/SWE #1/NZ #1 1983).
From the wiki: “‘Puttin’ On the Ritz’ is a popular song written and published in 1929 by Irving Berlin and first introduced by Harry Richman in the musical Puttin’ On the Ritz (1930). The expression was inspired by the opulent Ritz Hotel. Another hit version was recorded in 1930 by Leo Reisman & His Orchestra. Clark Gable performed the song on film (Idiot’s Delight) in 1939, but the song was most-famously performed (with new lyrics) by Fred Astaire, with whom the song is particularly associated, in the 1946 film Blue Skies. Gene Wilder and Peter Boyle teamed up in Mel Brooks’ Young Frankenstein (1974) to give the song a comedic spike.