Webb - who suffered a stroke last year - said the job is too much for him.
"Although my health is continuing to improve," wrote Webb in his resignation letter, "I believe the residents of District 5 deserve a Commissioner that can devote full time to representing their interests."
Webb was appointed to the Board of Commissioners in 2003 and was elected to four-year terms in 2004 and 2008.
"I will cherish and remember with fondness the friends made during my time on the board and the many accomplishments we were able to implement for the betterment of Wake County," wrote Webb.
The commissioner has held the respect of his peers for decades.
"A Tuskegee Airman, worked in state government, did a lot of things with integration back in the 60s and 70s, he was involved with the merger of the school system," said former chairman of the Wake County Democratic Party Jack Nichols.
Nichols, who is also now running for the board himself, says Webb's personal and professional experience will be sorely missed.
"You're losing that piece of history that he brought for this community to that board," he offered.
Even Webb's opponents say he will be missed.
"There's not anyone on our board that I have respected more than Mr. Webb," said commission member Tony Gurley.
Webb has been the swing vote on the board that's now split evenly between Democrats and Republicans.
Webb's absence from a meeting in December resulted in the so-called "Bladdergate" incident, when Gurley - a Republican - was voted chairman after Commissioner Betty Lou Ward - a Democrat - took a bathroom break during hours of deadlocked voting.
Now, Gurley says he sees politics in the timing of Webb's resignation.
"You could see it coming for months and months," he explained.
State law says if a candidate resigns within 60 days of an election, that person's party picks a replacement. Any other time, the voters decide. That 60 day window hit five days ago.
"If he had resigned last Thursday, that race would have been included on the November 2 ballot this year," said Gurley.
Now, it's almost a certainty that a Democrat will be appointed to Webb's seat and serve out his term until 2012.
But most, including Gurley, agree that whoever that Democrat is, he will have big shoes to fill.
"We have lost somebody who's had a lifelong commitment to public service and who is a very thoughtful experienced voice," said Nichols.