William Burck said Priebus' interview took place at Mueller's office.
"Mr. Priebus was voluntarily interviewed by Special Counsel Mueller's team today. He was happy to answer all of their questions," Burck said.
The team's interview of Priebus was expected after two unnamed sources told CNN investigators would begin talking to current and former White House staff about the probe in the coming weeks. The team also spoke to National Security Council chief of staff Keith Kellogg recently.
Mueller has said he's interested in also speaking to former press secretary Sean Spicer, communications director Hope Hicks, White House counsel Don McGahn, communications adviser Josh Raffel and associate counsel James Burnham.
Mueller is investigating whether the Trump campaign colluded with Moscow to interfere in the 2016 presidential election, as well as the firing of former FBI Director James Comey and a statement Trump made about Donald Trump Jr.'s meeting with a lawyer at one time linked to the Russian government, Politico reported.