Arp made his announcement Thursday, saying he wants to turn his attention to being a grandfather and "to do something else" besides public service, which he has been involved in for the past three decades.
Arp, 65, has been "involved in politics all my life," starting as grand jury foreman in 1974, serving on the County Commission from 1978-80 and as property assessor from 1980-2006 before being elected mayor.
Most of his adult life has been devoted to serving the county, although he said he also owned a tool business at one time.
But now, he said, "I have four grandkids. I want to go to ballgames and enjoy life."
Arp said he was first exposed to politics while working at a grocery store owned by an uncle. Another uncle owned another small business and "the political hacks would come by" giving him an interest in the political process.
"I just wanted to see Loudon County be a better place to live," he said.
Arp says the major accomplishments of his term have been the renovation of county schools, an increase in the county's fund balance and the paying off of several county notes.
He said that harsh criticism from some political factions in the county had no effect on his decision not to seek re-election.
"I am not scared of anyone, politically," he said.
Arp says he intends to remain politically involved in the county but has no plans to run for any specific office at this time.
Arp was elected in 2006, succeeding George Miller, who had served as county mayor for 20 years.
Arp's successor will be elected in August.