- Oct 1 Philadelphia Athletics seek 3rd straight World Series baseball title; beat St. Louis Cardinals, 6-2 in opener at Sportsman's Park; lose series, 4-3
- Oct 1 Spanish Cortes accept general female suffrage
- Oct 1 The second (and current) Waldorf-Astoria Hotel is opened in New York.
- Oct 4 Dick Tracy comic strip by Chester Gould debuts
- Oct 4 Juan Esteban Montero becomes President of Chile
- Oct 5 1st nonstop transpacific flight, Japan to Wash (Herndon & Pangborn)
- Oct 5 Paul Green's play "House of Connelly" premieres in NYC
- Oct 6 Joris van Severen forms Verdinaso (Union of Flemish National Solidarists)
- Oct 7 1st infra-red photograph, Rochester, NY
- Oct 10 A J Bennett hits H Garbarino for 1st scoring pass in Canada's Big 4
- Oct 10 Baseball World Series: St Louis Cardinals beat Philadelphia A's, 4-2 at Sportsman's Park for a 4 games to 3 series win
- Oct 10 William Waltons "Belshazzar's Feast" premieres in Leeds
- Oct 11 100,000 extreme-right Germans form "Harzburger Front"
- Oct 12 1st International Conference on Calendar Reform
Christ the Redeemer
Oct 12 Christ the Redeemer statue opens standing 30 meters high (98 ft) on top of Mount Corcovado overlooking Rio de Janeiro, built by engineer Heitor da Silva Costa
- Oct 13 Musical "Everybody's Welcome" with Tommy and Jimmy Dorsey premieres in NYC
Cavalcade
Oct 13 Noël Coward's play "Cavalcade" premieres in London
MVP Frankie Frisch
Oct 20 Frankie Frisch of the Cards named MVP
Mourning Becomes Electra
Oct 26 Eugene O'Neill's play cycle "Mourning Becomes Electra" premieres in NYC
Eugene Ormandy Debut
Oct 30 Eugene Ormandy makes his debut leading the Philadelphia Orchestra, substituting for an ailing Arturo Toscanini
- Oct 30 W2XB TV channel 1 in NYC, NY (NBC) begins broadcasting