The pair are expected to provide injury insurance and depth in practices.
"We think they're a great fit for us," Bulls coach Tom Thibodeau said. "Both are high character guys, both are shooters. And it's insurance for us. And it also gives us an opportunity to rest some guys in practice, if we choose to do that."
Pargo, a Chicago native who played 63 games for the Bulls last season, had knee surgery and did not stick with the New Orleans Hornets earlier this season.
The Bulls waived Lucas on Jan. 4 before his contract was guaranteed for the remainder of the season.
Meanwhile, Carlos Boozer, who has missed the last five games with a sprained left ankle, practiced Sunday.
"I feel good," Boozer said. "I went through practice a little bit. See how it feels [Monday when the Bulls host the Kings].
"The pain's still there. You don't want to be stupid and come back too soon and have a nagging injury. At the same time, if it's ready [Monday], I'd like to go, so we'll just have to wait and see how it goes [Monday]."
"Knowing me, I should try to play, but we'll see by [Monday] if the swelling goes down," said Gibson, who injured the toe in a collision during Friday's game against the Pacers. "If anything, I'll try to adjust and get as much treatment as possible, hope I can get back on the court early."
Nick Friedell covers the Bulls for ESPNChicago.com and ESPN 1000.