Joh was born in Philadelphia, Pennsylvania, and moved to San Diego, California as a young child.

[1] She attended Rancho Bernardo High School where she earned American Junior Golf Association (AJGA) HP Scholastic All-America honors.

She was a member of the 2008 U.S. Curtis Cup Team In August 2007, she finished tied for 21st at the Safeway Classic on the LPGA Tour.

[2] Joh was named 2008 Pac-10 Golfer of the Year, and captured her third All-America nod from the National Golf Coaches Association (NGCA) after leading the Bruins in every statistical category during the 2008 season.

She won again on the Futures Tour in 2011 at the South Shore Championship and had two top-30 finishes on the LPGA by the halfway point in the season.

This put her in 41st place on the season-ending money list, enough to earn full privileges on the LPGA Tour for the 2012 season.