Horn, a former schoolteacher, won the title by beating multi-division world champion Manny Pacquiao at Brisbane's Lang Park in July and improved his record to 18-0-1 in the more confined space of the city's convention centre.
Corcoran enjoyed success getting inside Horn in some wild early exchanges but the champion gradually took control of the contest.
Both fighters ended the bout with bloodied faces but Horn, who had lost four kilograms overnight to make weight, was ahead on the cards of all three judges when the fight ended.
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"He definitely pushed me in there," Horn told reporters.
"The timing was off at the start of the fight and I couldn't really get that range very well but as soon as I started working off that jab, I was able to break him down pretty easily."
Corcoran, who had cuts around his eyes checked by the doctor before the decisive round, looked disappointed when his corner brought an end to fight to leave him with a 17-2 record.
"Just too many cuts, I couldn't see the shots coming," the Englishman said. "Fair play to Jeff. He's a good fighter, I'll learn from it and I'll come again."
(Reporting by Nick Mulvenney, editing by Christian Radnedge)
