Siddique joined the University of Dhaka in 1974 and subsequently completed a second master's in finance from Southampton University.[7] He was promoted to assistant professor in 1986 and completed his PhD from Brunel University. From 1988 to 1992, he taught at Universiti Brunei Darussalam as an assistant professor.[7] He was promoted to associate professor in 1993.[7]
In 2004, Siddique filed a defamation suit against Motiur Rahman Rentu over his book, Amar Fashi Chai. In April 2007, a Dhaka court issued a verdict in favour of Siddique and awarded him 10 million taka in damages. After failing to get the compensation, Siddique filed a case seeking the confiscation of Rentu's properties on 10 August 2007.[8]
On 18 February 2016, Siddique described a string of 35 cases against Mafuz Anam, editor of The Daily Star, as "too much" while on BanglaVision.[11][17][18]