King is the son of former state senator Tom King. He holds a Bachelor's degree in finance from the University of Alabama (1974), a law degree from the Cumberland School of Law (1982), and a Master of Arts in public and private management from Birmingham-Southern College (1997).
Before going into law, King worked as an accountant in Saudi Arabia for Vulcan Materials. He joined the firm of King and King in 1982 and then left to work as a sole practitioner in 1991. He was elected to Probate Court, Place 2 in 2000 and was re-elected in 2006 and 2012. He was named Presiding Judge in 2007. In 2017 he announced that he would not seek a fourth term.
President Donald Trump appointed King to his 11-member Presidential Advisory Commission on Election Integrity.
King and his wife, Karen reside in Vestavia Hills and have one daughter, Kendall. The three of them were struck by a hit-and-run driver on Thanksgiving night in November 2018 while visiting Kendall in Denver, Colorado. Karen was killed, and Alan and Kendall were seriously injured.
- Walton, Val (October 26, 2006) "King says probate court needs leadership." The Birmingham News
- Bryant, Joseph D (November 8, 2006) "King unseats Gaines to lead probate court." The Birmingham News
- Hrynkiw, Ivana (September 28, 2017) "'This was a hard decision to make:' Longtime Jefferson County judge not to seek reelection in 2018." The Birmingham News
- Hrynkiw, Ivana (November 24, 2018) "Longtime Jefferson County judge, daughter recovering from hit-and-run." The Birmingham News