Following his college career at Marquette, he was a second-round draft choice (38th overall) of the Orlando Magic in the 2005 NBA Draft. His selection by the Magic mystified some critics, who argued that the team was overloading on point guards, already having Steve Francis and Jameer Nelson on their roster.
Diener made his NBA debut on December 2, 2005, playing 22 minutes and scoring twenty-three points in a loss to the Memphis Grizzlies.
On June 19, 2007, the Indiana Pacers signed Diener (who was a free agent) to a three-year deal reportedly worth $4.86 million.
He is represented by Washington D.C based agent, Doug Neustadt.
Diener's family has a storied basketball history, with many of his relatives coaching or playing at prominent universities. Consider:
In high school, Travis Diener was a USA Today Player of the Year: 2000 All-America High School Baseball as a pitcher and a shortstop.
Both Travis and Drake Diener engendered criticism in the 1990s when their families decided to redshirt them; both boys were pulled from the Fond du Lac public schools after 8th grade, homeschooled for the year and reentered as high school freshmen, not sophomores. Critics alleged they were held back in order to give an age advantage in high school sports.
|- | align="left" | 2005–06 | align="left" | Orlando | 23 || 0 || 10.7 || .420 || .439 || .833 || .9 || .7 || .3 || .0 || 3.8 |- | align="left" | 2006–07 | align="left" | Orlando | 26 || 0 || 11.1 || .425 || .360 || .800 || .7 || 1.3 || .2 || .0 || 3.8 |- | align="left" | 2007–08 | align="left" | Indiana | 66 || 21 || 20.5 || .370 || .318 || .901 || 1.7 || 3.8 || .5 || .1 || 6.9 |- | align="left" | Career | align="left" | | 115 || 21 || 16.4 || .383 || .344 || .880 || 1.3 || 2.6 || .4 || .0 || 5.6 |}