Zlatkov began playing football in his hometown Blagoevgrad at Pirin. In summer 2007, he started training with the first team and signed a professional contract, connecting him with the club until 2010. Zlatkov made his debut during the 2007–08 season on 10 May 2008 in a 2–2 away draw against Beroe. A few days later, he had a trial with Dynamo Kyiv, but did not do enough to secure a contract with the Ukrainian club. In June 2008, Zlatkov was sent to Pirin Gotse Delchevon loan for one year. In the 2008–09 season, he earned 27 appearances playing in the second division, scored seven goals and provided five assists.
Because of his good displays Zlatkov caught the eye of Minyor Pernik scouts. In May 2009, he signed a three-year contract with Minyor. On 17 January 2011 it was officially announced that he would spend 2 weeks trial with Maccabi Haifa. In August, he left the club.
Daniel Zlatkov signed a two-year contract with Botev Plovdiv on 25 August 2014. Daniel did not participate in any competitive games until 10 March 2015 due to an injury. He made an official debut during the 0-2 away win in the derby game against Lokomotiv Plovdiv. Five days later, on 15 March, Zlatkov was again included in the starting lineup and he assisted for the first goal scored by Milen Gamakov and had a solid overall performance during the important 2-0 win over CSKA Sofia. Daniel Zlatkov participated in 10 games in A Grupa during spring 2015 and because of his solid performance the fans of Botev Plovdiv selected him among the ten best players of the season. Zlatkov's contact expired in the summer of 2016 and the manager Nikolay Kostov decided to release him. After that Zlatkov joined Cherno More Varna and he even played in a few games. In September 2016, a week after the dismissal of Nikolay Kostov, Zlatkov returned again to Botev Plovdiv. On 23 February 2017, his contract was terminated by mutual consent.
After a brief stint as a MMA fighter, Daniel Zlatkov returned to football by joining Lokomotiv Sofia in February 2018, but the contract was not signed.
Zlatkov has made an appearance in Azis's music video for the song "Mykonos". In 2017 he entered in the 9th season of the Bulgarian VIP Brother. He was the seventh evicted in 10th place.
