After serving as the head coach at Stephen F. Austin State University for 15 years where she led the Ladyjacks to the 1986 NCAA Division II National Championship title, Baker returned to her alma mater TWU in the summer of 1995 as the head coach of the newly reinstated softball program. She immediately put all of her energy into designing a home field, recruiting and building a winning NCAA program. In nine seasons at TWU from 1997-2005, she guided the Pioneers to a 285-165-2 (.633) record and was named 1999 and 2002 Lone Star Conference Coach of the Year. Baker captured her 700th career win on March 2, 2003. Upon her retirement from collegiate coaching in 2005, Baker had compiled a 785-462-3 (.629) career record, establishing her among the winningest coaches in the NCAA record books.

Under Baker’s leadership, TWU had nine NFCA/ Louisville Slugger All-Americans, one NCAA Division II Diamond Catcher of the Year, 21 All-South Central Region selections, one South Central Region All-Tournament Team selection, three CoSIDA Academic All-Americans, three NFCA All-Academic Teams, 15 NFCA All-America Scholar Athletes, 53 All-LSC selections, 29 Academic All-LSC honorees, and 21 Commissioner’s Honor Roll awardees. Baker also coached three LSC Preseason Players of the Year, three LSC Players of the Year, one LSC Newcomer of the Year, one LSC Freshman of the Year, one LSC Rookie of the Year, one LSC Scholar Athlete of the Year, and 11 LSC All-Tournament Team members.

She was inducted into the TWU Athletics Hall of Fame in 1995, the National Fastpitch Coaches Association Hall of Fame in 1998, and the SFA Athletics Hall of Fame in 2009. In January 2000, Baker received the NCAA Silver Anniversary Award. In 2006, Baker was honored with the TWU Distinguished Alumni Award. She is a speaker, author, and a featured instructor in an eight-part softball fundamentals videotape series. In February 2019, TWU announced a gift of $500,000 - the largest gift to TWU Softball and the single largest gift to TWU Athletics by a living alumna - from the softball legend. The University renamed the softball field “Dianne Baker Field” and will host the dedication ceremony in September 2019.