The activists, mostly university students started their march at Georgetown University and headed towards the White House.
More than 1,000 students from across the country signed up to take part in a march.
Armed with slogans "climate justice now", they carried placards reading "don't tarnish the earth" with the aim to convince President Obama to reject the pipeline that will have dire consequences for the environment if built.
According to the environmentalist organizers 350.org, almost 400 protesters were arrested at the White House.
Prior to the arrests, the protesters had been warned that they should not block the sidewalk or strap themselves to the White House fence.
Keystone XL is a proposed tar sands pipeline that would connect western Canada to the US Gulf Coast. The 1,700-mile pipeline would carry 800,000 barrels of tar sands oil per day across the US to refineries in Texas.
Environmentalists say in addition to carbon-dioxide emissions caused by the Keystone XL pipeline, oil spills and their subsequent fallout also endanger communities nearby.
The project requires a Presidential Permit to move forward and activists are demanding US President Barack Obama to stand up to big oil corporations and stop the pipeline.
SHI/sHI