The 55-year-old travelled to the Spanish capital to see his former side take on Tottenham in the European decider at the Wanda Metropolitano Stadium.
But the ex-England winger's trip from the Greek island Santorini to Spain took mch longer than expected after his first flight was cancelled, leading to him spending a few hours lying outside the station before finally making it to Madrid.
"I was with my family in Santorini, I had to be here at 8:30am on Thursday morning," he told Liverpool Echo.
"My flight from Santorini got cancelled, so I then had to fly from Santorini to Athens, from Athens to Barcelona.
"Got to Barcelona 2am in the morning, my train, I had to get a train to Madrid, it was not until 5am, the train station is not open till 4am, from 2am until 4am I was lying on the floor outside the train station with a lot of homeless people before the train station opened.
"That's how committed I was to getting here."
Barnes says he was determined to get through his arduous journey to see Jurgen Klopp's team in action, taking a jibe at some of his fellow former stars who he believes would not have gone to such extreme lengths.
"I am not going to mention any names, about other divas who played for Liverpool, my former teammates who would have wanted to be in a five star hotel," he added.
"I slept on the floor of the train station for three hours, that is how much of a fan I am. I am not going to say who wouldn't have done it... Ian Rush... But apart from that, that is my commitment to the cause."