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Greenwald was asked by MSNBC anchor Kristen Welker to respond to critics that have charged Greenwald has "crossed a line" in defending Snowden and has become a "spokesman" for him.
Greenwald sniped back by blasting the network, charging that its own bias lies within its "24-hour" defense of President Barack Obama and the Democratic Party.
"I think that's ludicrous - that's what I say to that," Greenwald said.
"Every journalist has an agenda. We're on MSNBC now, where, close to 24 hours a day, the agenda of President Obama and the Democratic Party are promoted, defended, glorified, [and] the agenda of the Republican Party is undermined. That doesn't mean that the people who appear on MSNBC aren't journalists - they are."
Greenwald went on to say that he doesn't attempt to hide that he thinks Snowden's actions are "admirable" and "heroic."
Welker was perturbed by Greenwald's characterization of the network.
"I think the point is not so much about MSNBC and what happens here, but more that sometimes when you talk about Edward Snowden, you do defend him, and some people wonder if that crosses a line," she said.
"Sure, I do defend him - just like people on MSNBC defend President Obama and his officials and Democratic Party leaders 24 hours a day," Greenwald shot back.
"Not everyone on MSNBC does that 24 hours a day," Welker interjected.
"Not everyone, but a lot of people do," Greenwald said.
Greenwald has been outspoken in his defense of Snowden from the start of the surveillance debate. Most recently, Greenwald blasted TIME magazine on Twitter for choosing Pope Francis as its Person of the Year over Snowden. He called TIME the "cowards of the decade" for not selecting Snowden.
Here's video of Greenwald's appearance on MSNBC, via Politico: