The woman, who is said to have been 58 years old, was taken ill on the plane as it prepared to leave Palma for Edinburgh on Wednesday.
Paramedics boarded the aircraft to treat the passenger but she ‘sadly passed away’, Ryanair said.
The Foreign Office said officials were supporting the woman's family.
Ryanair told Sky News: ‘This flight from Palma to Edinburgh (22 May) was delayed ahead of take-off after a customer became ill prior to departure.
‘Paramedics boarded the aircraft after medical assistance was requested but the customer sadly passed away.
‘Ryanair extends its deepest sympathies to the bereaved and is providing any assistance required.’
A Foreign Office spokeswoman said: ‘Our consular staff are supporting the family of a British woman following her death in Spain.’
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