Son of James I. Clements and Annie May Carter, J.I. Clements, Jr. was born and raised in Ray City, GA. Clements received both his bachelor and master's degrees from Eastern Kentucky University. 

Clements joined the athletic department at Georgia Southern University as an assistant coach for the basketball team in 1948. However, in 1949, Clements was named head coach of the baseball team, during his younger brother Mason's last season playing third base for the Eagles.

Clements was not only a wearer of many hats in Eagle Nation, he also thoroughly enjoyed it. He served as Assistant Basketball Coach (1948-62), Head Baseball Coach (1949-1966), Athletic Business Manager (1957-1974) and Athletic Director from (1948-1974). Clements coached the Eagle Baseball from 1949–1966 and 1968. During his tenure he lead the baseball team to the 1962 National Association of Intercollegiate Athletics (NAIA) National Championship, which was the first national title for a Georgia Southern University team.

Clements coaching career record stands at 320-205. He led Georgia Southern to four NAIA District 25 championships. In 1960 and 1968, Clements led Georgia Southern to second place finishes and a third place standing in 1964. In addition to coaching, he has served as president of NAIA Baseball Coaches Association (1962-64) and was a member of the U.S. Olympic Baseball Committee in 1964.

J.I. Clements was inducted into the U.S. Baseball Federation Hall of Fame and the American Baseball Coaches Association Hall of Fame and was also voted NAIA National 'Coach of the Year' in 1963. As an athletic administrator at the University in 1970, Clements led Georgia Southern from NAIA to NCAA Division II status and to Division I level the following year. The baseball legend was rightfully named the 1974 Georgia Sports 'Administrator of the Year' by Georgia Athletic Hall of Fame.

Clements passed in 1974, and in 1985, officials named the university's baseball stadium in his honor. J.I. Clements Stadium still dons the stadium's forefront, even after the 2005 re-opening.  J.I. Clements is greatly recognized and appreciated for his efforts to enhance the educational and personal lives of student-athletes at Georgia Southern.