John B. Martin was born in 1948 at Red Oak, Iowa. He graduated from Chillicothe, Missouri High School in 1966 and received a B.A. degree from the University of Missouri in 1970. He graduated from the University of Iowa College of Law in 1973.
He commenced practicing law in June 1973 in Bloomfield, Iowa, first as a partner of Attorney John A. Stephens and later as a sole practitioner. He has been a member of the Iowa State Bar Association and American Bar Association since June 1973. He served as Attorney for the City of Bloomfield, Iowa for over eighteen years. On November 1, 2006 he was sworn in as Davis County Magistrate and served until May 1, 2018 when he resigned.
He is a former member of the Board of Directors of the Davis County Hospital Foundation. He is currently the secretary and member of the Board of Directors of Success Bank, formerly the Davis County Savings Bank, and has served as such for over thirty years.
He has been married to Susan Martin since December 27, 1970 and has two children, Jessica Martin-Rahlf of LaPorte City, Iowa and Ian Martin of Milwaukee, Wisconsin.