"FC Porto have been admitted to the 2009/10 UEFA Champions League, following a ruling by the UEFA Control and Disciplinary Body," UEFA said in a statement.
"The control and disciplinary body noted that it was... not authorised to rule on the admission or exclusion of Porto and has closed its investigation and struck it off the list of cases."
UEFA said the case dated back to the 2003/04 Portuguese championship involving alleged events in a case known as the Apito Dourado (Golden Whistle).
Porto were stripped of six domestic league points by Portuguese authorities for allegedly bribing referees during the 2003/04 season in a scandal which only came to light in the 2007/08 season.
In July last year, the Court of Arbitration for Sport (CAS) rejected an appeal by Portuguese clubs Benfica and Vitoria Guimaraes to have Porto banned from the 2008/09 Champions League.
UEFA said: "A club that wishes to take part in the UEFA Champions League must not have been directly and/or indirectly involved in any activity aimed at arranging or influencing the outcome of a match at national or international level and must confirm this to the UEFA administration in writing."
However, it said the ruling only applied to events after April 27, 2007 when the latest UEFA statutes took effect.
As Portuguese title holders, Porto will enter the Champions League at the group stage.
