[4][5] Milanov broke 60 metres for the first time in 2013, setting a Belgian under-23 record of 61.81 m in Vilvoorde and placing fifth at the European U23 Championships in Tampere.

[6] He continued to improve in 2014, breaking Jo Van Daele's old Belgian record (64.24 m) by eight centimetres in Lille on 23 February and improving the record further to 66.02 m at the FBK Games in Hengelo on 8 June; he was Belgian champion for the fourth consecutive year (60.57 m) and made his debut in the IAAF Diamond League.

[7] Milanov broke his own Belgian record again in Kessel-Lo on 25 April 2015, throwing 66.43 m and meeting the qualification standard for the 2015 World Championships in Beijing.

[12] On 29 August 2015 at the World Championships in Beijing, where he took silver, Milanov, improved his national record to 66.90 m.[13] Milanov started 2016 well, taking second place in the Doha Diamond League meeting in May, bettering his national record with a throw of 67.26 m.[14] In July, he won a silver medal at the 2016 European Athletics Championships in Amsterdam, The Netherlands with a throw of 65.71 m, beaten only by the world discus champion Piotr Malachowski.

In 2017, he failed to qualify for the final of the men's discus throw competition at the 2017 World Championships in Athletics in London ending in 14th place in the qualification round with a throw of 63.16 m.[17] Milanov missed the 2018 European Athletics Championships in Berlin, Germany due to injury.