The Magpies play Greek side Atromitos tonight in the Europa League qualifying playoff round, which will be the first European match the Magpies have played in five years.
Harper, who has played in the Champions League for the club, has said that it is "fantastic" for Newcastle to be back in continental competition.
"It's fantastic to be back in Europe," PA Sport quotes Harper as saying. "All credit to the gaffer and the players last year, they were outstanding and earned the right to be back here.
"It's great for me - I remember when we went out of Europe the last time, and a lot has happened in the not too many years between then and now.
"I know a lot of people, and I am sure the fans, will say that we are back where we belong, and hopefully we can stay in this competition as long as possible."
Harper has been a Newcastle player since 1993.