Jarrod Alexander joined the band from Dead Country and performed with them in Salt Lake City last night, Altpress reports.
It is unknown whether Alexander will play with the band on the remaining dates of their joint Honda Civic Tour with Blink-182, or whether he'll be a permanent replacement.
My Chemical Romance announced yesterday that they had sacked Pedicone after he was caught stealing from them.
"Some s**t happened and before the blogosphere gets all crazy with false statements and ridiculous opinions we want the true story to come from us," a statement read. "But please listen close because this is the only time we are ever going to talk about this.
"The relationship between My Chemical Romance and Michael Pedicone is over. He was caught red-handed stealing from the band and confessed to police after our show in Auburn, Washington."
Watch My Chemical Romance's video for 'Famous Last Words' below: