Investment banking took the top slot, followed by hedge funds, law, private equity/venture capital and asset managers.
Read MoreBest and worst tippers of food-delivery workers
"Looking at this list, these are industries notorious for their long work days," said Abby Hunt, GrubHub's director of public relations, during a phone interview. "It comes as no surprise that the ones with the long work days are going to be the ones to have their employees ordering more."
Employees show some serious java junkie behavior while on the clock. People place 110 percent more cappuccino orders while at work than while at home, 74 percent more coffee orders, 70 percent more iced coffee orders and 67 percent more latte orders, based on orders placed in the month ending July 14.
Read MoreFast food jobs pay $20 here... voluntarily
As the hours tick on, this over-representation of coffee increases. Employees burning the midnight oil from 10 p.m. to 2 a.m. are 500 percent more likely to order coffee while still at work than those at home.