The group of protesters arrested were among dozens at the event. They refused to move from in front of the TransCanada U.S. headquarters Monday while chanting slogans including "climate change has gone too far."
Police warned protesters they could face up to a $1,000 fine and 180 days in jail prior to arresting them, the Houston Chronicle said.
"They feel strongly enough that they're going to take that risk," said Amanda Starbuck, a spokeswoman for the Rainforest Action Network, which helped organize the protest.
Among those arrested were a former Exxon employee and a former Chevron geologist, both of whom quit their jobs because they were concerned about the environmental impact they were having.
The Keystone XL pipeline is a controversial plan that's yet to gain full approval from the Obama administration. It would transport oil produced from the tar pits in central Canada to U.S. refineries in Texas and elsewhere.
Environmental groups are adamantly opposed to the plan because tar sand oil extraction creates more emissions than normal oil drilling and the pipeline represents a risk if it leaks and spills oil in large quantities, the Chronicle said.