Speaking from his hospital bed, the world champion fighter promised he would be back in ring despite his injuries with a comeback mooted for the New Year.
Brook, 28 and from Sheffield, has been in hospital on the Spanish island since he was injured during the early hours of Thursday.
Speaking last night, he said: “I was out enjoying a night out before returning home to the UK, when I was the victim of an unprovoked attack.
“I’m devastated right now after being on such a high, having achieved my dream of becoming world champion in Los Angeles last month.
“This is obviously a major setback, but the thought of defending my title is what’s keeping me positive right now.
“I want to thank everyone for their support and ask for privacy for myself and my family at this time. Make no mistake - I will be back.”
After the incident Spain’s Guardia Civil said Brook had “lost a lot of blood”.
It is the second time Brook has been stabbed, after suffering injuries in an incident in his home city in 2007.
His promoter Eddie Hearn commented: “We were all glad to get out here and see Kell for ourselves. The important thing now is to get him home and after some rest begin physio on his injuries. His first defence was planned on December 6 which is now unrealistic but we fully expect Kell to be back in the ring early next year.”
Brook became IBF world welterweight champion last month with a stunning victory over American Shawn Porter. There had been widespread talks of a superfight with long-time rival Amir Khan at Wembley Stadium.