Career
Early career
Terziev started his football career in his home town at OFC Sliven 2000 and later he moved to Naftex Burgas. He made his debut for the senior squad, aged 15, in a match against Haskovo on 8 March 2008. He ended the season with 9 total appearances.
In April 2008 Newcastle United expressed an interest on him, and he went on trial at the club on 3 April.
He played with the youth team during the trial, however he was not picked up by the team Chernomorets Burgas
In July 2009, Terziev signed a five-year deal with Chernomorets Burgas.
Ludogorets Razgrad
On 12 August 2013, Terziev signed with Ludogorets Razgrad on a four-year deal for a reported fee of €500,000. He was given the number 55 jersey.
Terziev scored his first goal in the Champions League group phase on 26 November 2014, grabbing a 2–2 equalizer against Liverpool in the 88th minute, in an eventual 2–2 draw.
On 12 February 2016 he resigned with Ludogorets until 2019, after his contract was ending in the summer of 2016. On 7 October 2011, Terziev earned his first cap for Bulgaria in the 0–3 away loss against Ukraine in an exhibition match.