The singer - who performed a headline set on the NME/Radio One stage with his band Beady Eye - came out on stage and declared: "You're looking far too good Reading."
After receiving cheers from the crowd, the band performed their track 'Four Letter Word', taken from their 2010 debut album Different Gear, Still Speeding.
The usually outspoken star kept crowd interaction to a minimum throughout the set, which included renditions of their singles 'Beat Goes On', 'Millionaire' and 'The Roller'.
During the set Gallagher made a reference to his brother Noel's solo career. NME quoted the singer as stating that his brother was probably "somewhere over there playing a f**king acoustic guitar."
The jibe comes days after Liam dropped a lawsuit against his brother over claims he made of the circumstances surrounding Oasis's reasons to pull out of a performance at V Festival back in 2009.
Digital Spy is bringing you news from Reading Festival 2011 all weekend. Click here to read our full coverage of the music event.
Watch Beady Eye perform 'The Roller' at Reading Festival 2011 below: