The 10-second blast was from when the universe was only 630 million years old.
NASA's Swift satellite spotted the gamma-ray burst, an explosion of high-powered radiation, on April 23.
Then ground telescopes watched the X-ray afterglow and calculated it had traveled 13.035 billion light-years to get here.
The event (dubbed GRB 090423) is the most distant cosmic explosion ever witnessed, beating old records by 100 or 200 million light-years.
"It was a true blast from the past," said Swift's lead scientist Neil Gehrels, at NASA's Goddard Space Flight Center in Greenbelt, Md.
NASA astrophysicist Neil Gehrels said the star's fiery death gave birth to a black hole.
The star was only 1 million years old or so and was about 30 times the size of our sun.