The 61-year-old, Catalan leader from 2010 until last year, was convicted ofcivil disobedience for organising the poll in the northeastern Spanish region and ordered to pay a fine of €36,000.
Mas, who was Catalan president president from 2010 to 2016, went on trial last month with two former members of hisgovernment accused of serious civil disobedience and misconduct for having organised a symbolic, non-binding referendum in November 2014 despite a ban by Spain's Constitutional Court, which deemed it illegal.
Artur Mas (C), former Catalan vice-president of Catalan Government Joana Ortega (R) and former Minister of Education of the Catalan Government Irene Rigau react as they leave the TSJC (Superior Court of Catalonia. Photo: AFP
The sentence has banned him from holding public office for two years. Irene Rigau was banned from 18 months and Joana Ortega for one year and nine months.
The sentences can be appealed.
"In the Spanish state, people are hounded for their ideas," Mas said, vowing to take the case to the European Court of Human Rights if necessary.
Spanish Prime Minister Mariano Rajoy of the conservative Popular Party said he welcomed the fact that "impunity" had not won out.
During the trial, which saw tens of thousands of pro-independence protestors gather outside the court in Barcelona, Mas accepted full responsibilty for staging the vote.
"I am responsible for everything," Mas had told the court, speaking in Catalaneven when the judge addressed him in Spanish.
"My initiative and that of the government had deep, clear and purely democratic roots."
Prosecutors had called for Mas to be banned from holding publicoffice for nine to 10 years, while defence argued that they were merely defending "the right to freedom of expression" for Catalans, many of whom want a say in the future of their7.5 million-strong region.
Catalonia, a region with its own language and customs, has long demanded greater autonomy.
But in recent years, tensions with Madrid have markedly increased, as have calls for outright independence, culminating with the election in 2015 of a pro-independence government in Catalonia backed by a majority separatist parliament.
A watershed moment was in 2010, when Spain's Constitutional Court watered down a special statute awarded to Catalonia in 2006 under the Socialist government, giving it more powers.
Supporters of independence slammed what they said was "judicial harassment"and asked for a referendum similar to the one organised in Scotland in 2014.
After the Constitutional Court banned that, Mas and his associates instead held the non-binding vote anyway.
"There was no intention to commit any offence or disobey anyone," Mas told the court, adding his government just wanted to "promote citizen participation by all means possible."
But prosecutors point to the fact that the regional government requisitioned schools to set up polling booths and provided 7,000 computers as proof that it was involved -- a matter that was not addressed by Mas and his two former associates in court.
In the end, more than 80 percent of those who cast their ballot in the 2014vote did so for independence -- although just 2.3 million people out of atotal of 6.3 million eligible voters took part.
Catalonia's current government has promised to hold a referendum inSeptember -- a binding one this time, with or without Madrid's consent.
But how exactly it will go ahead is unclear, as the conservative government of Prime Minister Mariano Rajoy insists that this type of local, one-region-only referendum is unconstitutional, and has vowed never to allow an act that would risk the unity of Spain.
Rajoy has tasked his deputy prime minister, Soraya Saenz de Santamaria, to start regular talks with Catalan authorities, but so far these have not yielded any results.
The Catalans themselves remain divided over the issue -- 44.9 percent want independence while 45.1 percent don't, according to a recent poll conducted by a Catalan public institute.
A large majority, however, wants a referendum.