Rivera became mayor in 1976, defeating mayor Manuel Aponte Borrero. His main concerns towards Bayamon were in the tourism and business industries. During his 24 year tenure, many buildings and other types of structures were inaugurated, including the Parque De Las Ciencias, the Parque del Trensito (which has Puerto Rico's only running train and a DC-3 plane formely used by United Airlines), the city hall, which is a building that crosses over an avenue, the Ruben Rodriguez Coliseum, the Canton Mall, a small suspension bridge and many others. In addition, a large industrial park with such notable companies as 7UP and Wrangler also opened, in the area known as Lomas Verdes. 7UP has a bottling facility there.
Rivera, a member of the Progressive New Party (PNP), was asked several times by party officials to run for governor. He pointed out his lack of knowledge in English as the reason why he always declined. He is, however, credited as being one of the mayors in Puerto Rico who was able to attract the most voters from the other parties, as he won the 1980, 1984,1988, 1992 and 1996 elections by land slides.
In 2000, he announced he would not run for mayor anymore, and his son, Ramon Luis Rivera Jr was then elected as mayor. Rivera Jr. has held that position ever since. Rivera has since retired from public life.