"It was detected early and he has been surgically cured," Jodi Gottlieb told People. "Dustin is feeling great and is in good health.
The two-time Oscar winner, 75, will now undergo doctor-recommended treatment to minimise the chance of a recurrence in the future.
Dustin's rep didn't disclose the type of cancer he had been diagnosed with, and there had been no previous reports of the acting legend falling ill.
Meanwhile, the star has been keeping busy. He's been promoting his latest film, Quartet, which marked his directorial debut, and last month Jon Favreau posted two videos of Dustin on the set of his new movie, Chef.
The comedy, which is due out in May next year, also stars Scarlett Johansson, Robert Downey Jr and Sofia Vergara.
In the autumn, the six-time Golden Globe winner will start shooting Roald Dahl's Esio Trot alongside Judi Dench.
Dustin will have had the support of his family during his cancer treatment. He has been married for 32 years to his wife Lisa, and the couple have four children together; Jacob, 32, Rebecca, 30, Maxwell, 28 and 25-year-old Alexandra.
The star is also father to Jenna and step-daughter Karina from his previous marriage to Anne Byrne.