On the 222nd lap, Dixon drove under Marco Andretti coming out of the third turn to get in front.
Near the same spot a lap later, Ryan Hunter-Reay was on the bottom of the high-banked track trying to get past Andretti. But Hunter-Reay's car suddenly darted up into Andretti, sending both of them into the wall.
"He gave me the bottom line on the backstretch, then he really turned early," Hunter-Reay said.
"He said that he gave me enough room. I didn't feel he did. Moving down to avoid contact, the car got unhinged." IndyCar Series crews were unable to get the track cleared before the 228-lap race.
It was the 13th career victory for Dixon, and third this season for the Indianapolis 500 champion and series points leader.
Any concerns about running out of fuel were eliminated when Hunter-Reay and Andretti crashed.
"I won at Texas. I can't believe it," Dixon said.
"Everybody was trying to save fuel. We were probably going to be a little short." Dixon, the polesitter for the race, said Andretti "left it wide open" when the Target Chip Ganassi driver was able to make what ended up being the winning past.
Helio Castroneves, the only driver to finish in the top five of every race, managed to avoid the race-ending crash and finished second. His Penske teammate, Ryan Briscoe, finished third a week after getting his first IndyCar Series win.
Dan Wheldon, Dixon's teammate who was driving with a sprained right foot after a crash in practice Friday, was fourth. Tony Kanaan was fifth.
Danica Patrick, whose third-place finish at Texas last June was her career best then, was 10th.
