Hudson, 31, agreed Thursday to a new Minor League contract with Kansas City and a non-roster invitation to Major League Spring Training.
The right-hander became a free agent last month rather than accepting an outright assignment to Triple-A Omaha. However, he elected to return to the Royals. Hudson initially joined Kansas City as a free agent after the Reds released him in the spring of 2006.
Hudson did not pitch in a game in 2008 as he recuperated from shoulder surgery, and he made only one appearance in the Majors in '07.
In his last full, healthy season, Hudson posted a 5.12 ERA in 102 innings for the Royals in 2006. He made 15 starts and 11 relief appearances that year.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.