The text, entitled "Ours first", was put to a popular vote by the populist right-wing Swiss People's Party (SVP), and was accepted on Sunday by 58 percent of voters in the Italian-speaking region, which borders Italy.
The text calls for changing the Ticino constitution to stipulate that when candidates for a job have the same professional qualifications, employers should prioritize those living in the canton over those living abroad, in a bid to fight "wage dumping" and unemployment.
Roberto Maroni, who heads Italy's northern Lombardy region and who is a member of the Lega Nord regionalist party, spoke out on social media, saying he accepted the outcome of the Ticino popular vote, but vowed to begin Monday studying "adequate counter-measures".
On Sunday evening, Italian Foreign Minister Paolo Gentiloni stressed on Twitter that the referendum would have no immediate practical implications.
But he warned that "without freedom of movement of people, Swiss-EU relations will be at risk."
In the run-up to the vote, SVP argued that the initiative aimed to find a solution for the Ticino labour market while waiting for measures at a federal level to kick in.
Of the 200,000 positions in Ticino, 63,000 are today held by cross-border workers, according to Swiss public broadcaster RTS.
Unemployment meanwhile stood at 3.2 percent in Ticino in August, compared to 3.1 percent for Switzerland overall, according to statistics from the Swiss economy ministry.
Following Sunday's vote, Ticino authorities cautioned that it would be difficult to apply the text voted through due to "a harmonisation problem especially in relation to the federal laws, which our canton is obliged to respect."
Swiss media also stressed on Monday that for Ticino to change its constitution, the canton would need a green light from Bern, something that is far from assured.
The Swiss government could not be reached immediately for comment, but is unlikely to look kindly at the Ticino vote, as it struggles to repair frayed relations with the EU.
Bern has for months been trying to figure out how to apply a decision voted through at a national level in February 2014 that would dramatically curb immigration from the block.