He cited Jesus, who found fulfilment as a carpenter.
"Lord, you always had work, you were a carpenter and you were happy. But we don't have work, our dignity is being robbed, an unjust system is robbing us of hope. Lord, do not leave us on our own. Lord Jesus, give us jobs and teach us to fight for work."
The Pope met unemployed miners in hard hats, as well as Francesco Mattana, a 45-year-old married father of three who lost his job with an alternative energy company four years ago.
Mattana told the South American pontiff that not having a job "oppresses you and wears you out to the depths of your soul".
Later, the Pope celebrated Mass for about 300,000 people outside the city's cathedral, telling them: "We don't want this globalised economic system which does us so much harm. Men and women have to be at the centre [of an economic system] as God wants, not money.
"The world has become an idolater of this god called money."
Sardinia was not alone in its struggle with high unemployment and the breakdown of communities, he said, as the same problems existed throughout Europe and beyond.