The mutation of the coronavirus was detected in a 20-year-old Swiss woman who had travelled from South Africa via Frankfurt to the island, the German-language Mallorca-Zeitung newspaper reported on Thursday.
The traveller is fully vaccinated. A coronavirus test conducted in Germany delivered a negative result, but a test in Mallorca came up as positive.
Together with her companion, whose test was negative, the woman must now spend two weeks in quarantine.
Several cases of Omicron had already been registered on the Spanish mainland in previous days.
Coronavirus numbers have risen in Mallorca, as in the rest of the country, which has a vaccination rate of almost 80 percent. The seven-day incidence rate of new infections per 100,000 inhabitants on the island is currently 140.
In order to counteract the development, the regional government wants to make the presentation of a coronavirus pass showing proof of vaccination, recovery from Covid-19 or a recent negative test mandatory in future when entering pubs, restaurants, gyms and other indoor spaces with a capacity of more than 50 people.
A decision by the judiciary on the plan is still pending.