The partnership, which is now live (www.hotelesib.com) will provide iberia.com with a direct link to lastminute.com's database of hotels, and relevant offers will appear alongside each of Iberia's flight destinations.
This is just one in a series of 'white-label' alliances that will enable lastminute.com to use its technology to create new revenue streams, without additional capital expenditure.
Brent Hoberman, chief executive officer of lastminute.com, said: "Our technology platform, combined with some great value deals and comprehensive product ranges in all major European languages, can be of benefit to a wide range of partners.
"We will be further leveraging this technology with other partners," he added.
Lastminute.com announced similar partnerships in 2003 with Tesco.com and Egg in the UK, plus Fnac in France.