Trinidad started his political career when he was elected as councilor in 1964. He was elected three times for the same post. He was elected as a Vice Mayor from 1980 to 1986 and from 1992 to 1998. Trinidad ran for Mayor in 1988, but lost to
Pablo Cuneta. In 2000, due to the failing health of then-Mayor
Jovito Claudio, a
recall election was commenced, and he won. Trinidad served for three terms, (with the exception of his term after his victory on
2000 recall election), from 2001–2004, 2004–2007, and 2007–2010. From September 2006 to May 2007, he was suspended alongside 11 other Pasay city officials over the alleged irregularities in garbage collection and disposal contracts in 2004 and 2005 amounting to . He ran for supposedly fourth non-consecutive term in 2010, but lost to Vice Mayor
Antonino Calixto. He ran again in 2013 but lost to the same once again. ==Controversy==