The committee issued the bipartisan subpoena Wednesday calling for Watkins to testify Sept. 5 on what he's doing to combat the forum's rampant extremism.
The El Paso gunman is believed to have posted a racist manifesto to the online message board before opening fire at a Walmart.
The House Homeland Security Committee wrote to Jim Watkins, owner of the online extremist site that's been linked to at least three mass shootings this year.
The shooter may have acted alone, but he is part of a network that stretches from Christchurch to Charlottesville.
The suspected gunman behind the El Paso massacre is believed to have drawn inspiration from 8chan, an online forum where bigotry is celebrated.
8chan radicals are accused of committing three mass shootings this year alone.