And he brought some mates -- around a dozen rams were came with them to the Santa Barbara offices.
At one point, the sheep fled from the protest and ran across a main road that was close by.
Police were called to the protest, and the two Australians were eventually asked to take the sheep away.
The rams were used to highlight an upcoming court case, in which Deckers has sued Australian Eddie Oygur for calling his shoes Ugg Australia -- a brand that Deckers bought the rights to back in the 1990s.
But Oygur and Xenophon, standing next to a sign that read "Deckers — a global giant stomping on Eddie's small fair dinkum Down Under business", believe the small Australian operator has a case.
Speaking to The Today Show, the two explained that they were one of the first ones to stand up to Deckers.
"No one's actually taken on Deckers, because when Deckers sues people most people roll over, because it's a multi-billion dollar corporation and in this case Eddie's standing up to them and counter-suing them saying they shouldn't actually have the right to use the name Ugg," said Xenophon, who last week announced he would quit the federal Senate and run for a seat in South Australia.
"So, if Eddie succeeds it really will be like David and Goliath, he will bring down a global giant."
"[Deckers] employ thousands of people globally. Their brand, Ugg Australia, makes Ugg boots in China and Vietnam, yet they are suing Eddie saying that you cannot sell Ugg boots anywhere else in the world because we own the trademark," he continued.
Deckers sells $1.5 billion worth of the boots every year.
Xenophon also said that he is paying for the trip to California himself.