Emma Haruka Iwao, a Google employee from Japan, found the new digits with the help of the company's cloud computing service.
Pi is the number you get when you divide a circle's circumference by its diameter.
The first digits, 3.14, are well known but the number is infinitely long.
Extending the known sequence of digits in pi is very difficult because the number follows no set pattern.
Pi is used in engineering, physics, supercomputing and space exploration - because its value can be used in calculations for waves, circles and cylinders.
The pursuit of longer versions of pi is a long-standing pastime among mathematicians. And Ms Iwao said she had been fascinated by the number since she had been a child.
The calculation required 170TB of data (for comparison, 200,000 music tracks take up 1TB) and took 25 virtual machines 121 days to complete.
"I feel very surprised," Ms Iwao, who has worked at Google for the past three years, said of her achievement.
"I am still trying to adjust to the reality. The world record has been really hard."
But she still hopes to expand on her work.
"There is no end with pi, I would love to try with more digits," she told BBC News.
It would take 332,064 years to say the 31.4 trillion digit number.
Google announced the news in a blog on Pi Day (14 March - "3.14" in American date notation).