Lawyers who briefed reporters outside the court quoted Judge OP Saini as holding that there was no available evidence against any of the accused and that "the prosecution has failed miserably" to prove its case.
"I have no hesitation in holding that the prosecution has miserably failed to prove the charges and all the accused are acquitted of the charges," said Judge OP Saini.
A Raja was reportedly in tears. "Justice has prevailed,"said M Kanimozhi, parliamentarian and daughter of DMK chief M Karunanidhi. Outside court, hundreds of their supporters had gathered in support.
The 2G allegations, which emerged during the second term of Dr Manmohan Singh's Congress-led coalition government at the centre, became a key constituent of the image of the administration as one seeped in systemic graft.
Named along with Mr Raja in the scandal were promoters and top executives of some of India's best-known telecoms. Ms Kanimozhi was accused of corruption too; the CBI said that a 200-crore bribe paid by a telecom to Mr Raja was deposited in a TV channel in Chennai that is owned in part by her.
Mr Raja was arrested in 2011 and spent nearly one year in prison before getting bail.