Salwai, along with former government ministers Matai Seremaiah and Jerome Ludvaune, and a former MP, Tom Kerr, had been charged with corruption and bribery.
The charges stemmed from a 2019 complaint by the current deputy prime minister Ishmael Kalsakau, who was Opposition Leader at the time.
Ishmael claimed that Salwai bribed two of the other MPs to withdraw their signatures from a motion of no confidence against him.
In December, the Supreme Court ruled that there was no case.
The public prosecutor, Josiah Naigulevu, filed an appeal which the Appeal Court has now dismissed.
In a separate case, Salwai was given a suspended jail sentence for perjury in December.
At sentencing earlier this month, Justice Wiltens handed him a two years and three months suspended sentence.