Portrait of legendary fighter John L. Sullivan, aka "The Boston Strong Boy", and his meteoric rise to become the first gloved World Heavyweight Champion. But the famed boxer is no match for the two women with holds on him, love struck actress Kathy Harkness and the real love of his life, beautiful but unyielding Anne Livingstone.
| Actor | Role |
|---|---|
 Linda DarnellAnne Livingston | Anne Livingston |
 Greg McClureJohn L. Sullivan | John L. Sullivan |
 Barbara BrittonKathy Harkness | Kathy Harkness |
 Otto KrugerRichard Martin | Richard Martin |
 Wallace FordMcManus | McManus |
 George MathewsJohn Flood | John Flood |
 Robert BarratBilly Muldoon | Billy Muldoon |
 Joel FriedkinMichael Sullivan | Michael Sullivan |
| SSimon SemenoffMons. Claire | Mons. Claire |
 Harry CrockerArthur Brisbane | Arthur Brisbane |
 Rory CalhounJames J. 'Gentleman Jim' Corbett | James J. 'Gentleman Jim' Corbett |
 J.M. KerriganFather O'Malley | Father O'Malley |
 Fritz FeldClaire's manager | Claire's manager |
| LLee SullivanMickey Steele | Mickey Steele |
 Eddie KanePromoter | Promoter |
 Jerry MarenMidget | Midget |
 Ernie AdamsWaiter (uncredited) | Waiter (uncredited) |
| GGuy Bellis(uncredited) | (uncredited) |
 Ted BillingsFight Spectator (uncredited) | Fight Spectator (uncredited) |
 Freddie Steele(uncredited) | (uncredited) |