Jeff Mulligan announced Monday on his blog that his resignation will be effective on July 31.
Mulligan says he thinks he can make a bigger contribution through his consulting firm, which he says he plans to expand.
Mulligan was elected in 2009 and was acclaimed for a second term in 2012.
Mulligan had said Monday that Lloydminster's deputy mayor, Rob Saunders, would assume the duties of mayor until the next municipal election.
But late Monday, the City of Lloydminster announced that it will hold a byelection on Wednesday, Oct. 16, 2013 for the position of mayor as well as for a Lloydminster Catholic School Board member.
Lloydminster straddles the Alberta-Saskatchewan boundary, but its elections are on the Saskatchewan cycle, and so the next municipal election won't occur until 2016.
Mulligan says he considers his greatest accomplishment as mayor was changing and modernizing the way the city interacts with the public.
"We had a much broader social media presence. We introduced the communications team. We did a lot of work in those areas so that we could really hang an 'open for business' sign on the city," Mulligan said Monday night.
"Rather than a permission-granting culture, we've tried to migrate it to a service culture, and I'm very proud of that."
While the announcement to vacate the mayor's seat is short notice, Mulligan says it is important that he not be accused of possible conflicts of interest.
"I want to make it very clear that I'm not involved in any decisions from this day forward that might affect my future life," Mulligan said.
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