The hotel heiress was asked by producers of the hit reality TV show to appear alongside her aunts, Kyle and Kim Richards, but she was forced to decline because she is out of the country on business.
A source said: "Paris was asked to be a part of the finale which will take place in mid-July. She is a big fan of the show and totally supports her family appearing on it, but had to decline because she will be out of the country. Paris will be extremely busy promoting her new album, and just has too much going on right now to commit to taking on anymore projects."
Kyle and Kim were also disappointed Paris couldn't take part as they know she would have been a hit.
The source added to RadarOnline.com: "Producers were hopeful Paris would be able to be a part of the finale, which they could have promoted and publicized. Paris definitely would have greatly bolstered the ratings for the finale, but, her schedule just couldn't accommodate it. Paris' aunts, Kim and Kyle also wanted her to be on the show, but they completely understand."