Former Bangkok governor Apirak Kosayodhin, another defendant in the case, was acquitted.
Pracha, a member of the family that owns Channel 3, and Mr Apirak were among five former top officials and an Austrian company named as defendants in the case filed in August 2011 by the National Anti-Corruption Commission (NACC) with the Supreme Court's Criminal Division for Holders of Political Positions.
The three other defendants were former interior minister Pokin Polakul, former commerce minister Watana Muangsook, former head of the BMA's Disaster Prevention and Relief Department Athilak Tanchukiat, and the Austrian supplier Steyr-Daimler-Puch Spezialfahrzeug AG.
The five were charged with malfeasance in violation of Article 157 of the Criminal Code and the Price Collusion Act in connection with the procurement of fire trucks and boats and other disaster relief equipment worth 6.7 billion baht for the BMA.
The NACC's investigation concluded that the 315 fire trucks and 30 fire boats were procured at an inflated price.
The nine-member court bench found Mr Pracha and Pol Maj Gen Athilak guilty. Pracha was given a 12 year prison sentence and Athilak 10 years.
The court dismissed all charges against other defendants, except Steyr Co, and acquitted them in the scandalous corruption case that has dragged on for almost a decade. Steyr Co failed to send representatives to answer charges, so the court is yet to rule on their case.
According to the ruling, Mr Pracha and Pol Maj Gen Athilak pushed for the purchase of 315 fire engines and 30 fire-fighting boats from Steyr Co without comparing price differences with other manufacturers, which equated to unfair trade practice and price collusion.
The procurement benefited the Austrian company, because the price of the machines was 48.77 per cent higher than the cost of the same goods previously bought by the Interior Ministry from local manufacturers
The court previously set Aug 6 to read the verdict, but adjourned to Tuesday because Pracha did not turn up to hear the judgement. He also failed to show up at the court on Tuesday.
The court issued an arrest warrant for the former deputy minister and fined his guarantor 2 million baht after his no-show on Aug 6 on the grounds that he failed to give reasons for being absent, and therefore deliberately failed to attend. He is rumoured to have fled to a location in Europe.
Sitthichoke Srichareon, the NACC lawyer who brought the fire boats and trucks corruption case to court, told Khao Sod newspaper that Pracha asked permission from the court to travel to Hong Kong and Macau on July 31, promising he would return to Thailand to hear the Aug 6 verdict.
“I believe Pracha will not appear to hear the ruling and may have fled to the US or Europe by now. I don’t think [police] can go after him and catch him,” Mr Sitthichoke said, before the reading of the judgement on Tuesday.
He said the statute of limitations for a person fleeing an arrest warrant is 10 years.
The late former prime minister Samak Sundaravej signed off on the deal on Aug 27, 2004, the last day of his tenure as Bangkok governor. Mr Apirak, who succeeded him, signed the letter of credit.
Mr Apirak, who is a Democrat Party deputy leader, told reporters after the court ruling: "I thank the court for giving me justice."