Alonso was banned for the Champions League final against Atletico Madrid in May after picking up a needless caution in Real's semi-final second-leg victory over Bayern Munich.
During the final in Lisbon, Alonso leapt from his seat in the stands and raced down the touchline to celebrate Gareth Bale's goal with his team-mates in the 4-1 win, incurring a further European suspension.
Real appealed that latest punishment, but European football's governing body confirmed on Friday that the original decision had been upheld, meaning Alonso will miss the clash with Sevilla at Cardiff City Stadium next week.
"The UEFA Appeals Body has rejected the appeal of Real Madrid CF against the suspension of their player Xabi Alonso," a brief statement read.
"Consequently, the decision by the UEFA Control, Ethics and Disciplinary Body announced on July 17 has been confirmed and Alonso will be suspended for the next UEFA competition match for which he will be eligible.
"The ban is to be served during the UEFA Super Cup final between Real Madrid and Sevilla FC on August 12."
