Milanov made his league debut in 2003. With Levski Sofia he reached the quarter finals of UEFA Cup in 2005–06. Next season, Levski Sofia reached the group-stage of UEFA Champions League, becoming the first Bulgarian team that reached the groups. He became a Champion of Bulgaria in 2009.
Milanov joined Vaslui on 14 January 2010 on a -year contract. The deal was reported by media to be worth $350,000. He was seen as the perfect substitute for Vaslui's captain Buhuş, whose long-term injury would keep him out from the field for the rest of the season. He made his league debut against Gaz Metan Mediaş, wearing the number 20 for Vaslui. He did not missed a single match for his new team, and helped Vaslui finishing third in Liga I, and reaching the Romanian Cup final, eventually lost at the penalty shootout. After Buhuş's departure, he established himself as Vaslui's first-choice right back. On 23 July 2010, in Liga I's opening match, Milanov received his first red card since his arrival in Vaslui. Following Luz's long term-injury and Bălace's bad shape, Milanov was sent to play on the left side. However, because of Papp's unsuccessful try out on the right side, Milanov was sent back on his favourite position. In his second season in Vaslui, he ended third in Liga I, after a long battle, between Oţelul Galaţi, Poli Timişoara and SC Vaslui, for their first championship. On 23 July 2011, Milanov received his second red card, in Vaslui's opening match against Rapid București. On 19 August, he scored his first goal for Vaslui, against Sparta Prague helping his team qualify for the first time to the UEFA Europa League's Group Stages.
Milanov returned to Levski Sofia in early September 2015 and played for the Blues during the autumn part of the 2015–16 A Group, receiving praise for his performance.
On 30 December 2015, Milanov signed an 18-month contract with Cypriot First Division champions APOEL. He made his debut on 10 January 2016, playing the full 90 minutes in APOEL's 2–1 away victory against Aris Limassol for the Cypriot First Division. A few months after joining APOEL, he crowned champion as his team managed to win the Cypriot First Division title for a fourth time in the row. On 2 March 2017, Milanov signed a two-year contract extension with APOEL, running until 31 May 2019.
Levski Sofia
After agreeing with APOEL to rescind his contract, Milanov returned again to Levski Sofia. On 11 February 2019 he signed a 1,5-year contract with the club. On 23 June 2020 he played his last professional match against Lokomotiv Plovdiv in a semi-final Cup tie, finishing 0-0. After the match, he stated that a lung disease made him retire.
International career
Milanov started playing for the Bulgarian national team in 2006, and has been capped 28 times during his international career. He announced his retirement from the national team on 21 March 2017, at the age of 32.
