In August 2003, Lonhro began his 5yo season with his second win in the AJC Warwick S-Gr2 (1,400m). Two weeks later, it was on to the Chelmsford S-Gr2 (1,600m) where he again won. The WFA George Main Stakes-Gr1 (1,600m) at Randwick and a rematch with Grand Armee was next. In a slowly run race, Lonhro defeated Grand Armee by three lengths, with a further two lengths to the previous year's winner, Defier, in third. It was then to back to Melbourne for the Caulfield Stakes-Gr1 (2,000m), where Lonhro beat Mummify. Winning by two lengths, he became the first horse to win consecutive Caulfield Stakes since Kingston Town in 1981 and 1982.