The actor was forced to leave the series after experiencing a recurrence of non-Hodgkin lymphoma for which he must undergo "aggressive treatment", reports People.
"It's with a deep sense of disappointment that I must step aside from such an exceptional project as Spartacus and all the wonderful people involved," he said in a statement.
"It seems that it is time for myself and my family to embark on another extraordinary journey."
Upon hearing news of Whitfield's cancer diagnosis, Starz CEO Chris Albrecht said: "Our hearts and prayers are with Andy and his family during this difficult time.
"Andy is not only an incredible actor whose portrayal of Spartacus made an indelible impression on Starz audiences, he is also an amazing human being whose courage, strength and grace in the face of adversity have inspired all of us."