Police fired tear gas and fought running battles with some 2,000 supporters of Tahir-ul Qadri.
Reports say the plane carrying Qadri circled above the airport for hours before it was finally diverted to Lahore.
Qadri's arrival comes a week after eight people were killed when his followers clashed with police in the eastern city of Lahore.
In remarks issued ahead of his return, Qadri -- who champions religious tolerance and once issued a fatwa against the Taliban -- said he was ready to lead a "revolution" against the government and praised the army.
Qadri's sudden ascent to prominence has prompted speculation that he is being supported by the country's powerful military to keep civilian authorities in check.