[19] Shmailov represented Israel at the 2024 Summer Olympics in Paris in judo in the men's 66 kg event (where he beat Morocco’s Abderrahmane Boushita in his first match, lost to Tajikistan’s Nurali Emomali in his round of 16 match, and came in 9th), and in the mixed team event in which Team Israel came in ninth.

He recognized Shmailov's potential and recommended that he transfer to train at the famous Wingate Institute under better conditions, which he did the following year.

[20][4] Shmailov's coaches are Israeli former Olympic bronze medalist Oren Smadja, Artur Kataev, and Eran Vardi.

[21] On 19 September, at the age of 20, Shmailov took part in the 2014 European Junior Championships which was held in Bucharest, Romania, and won the gold medal after winning every match by ippon.

[24][25][26] On 14 November, at 20 years old he won the 2014 European U23 Championships in Wrocław, Poland, after defeating Andraž Jereb of Slovenia in the final.

[30][31] He defeated former world champion Georgii Zantaraia in the semi-final and lost to Mongolia's Davaadorjiin Tömörkhüleg in the final.

On 7 October, he took part in Israel's national championship and won the gold medal after he defeated Tohar Butbul in the final.

[21] After a long contest with Tal Flicker, Shmailov was chosen to represent Israel at the 2020 Summer Olympics in Tokyo in the men's 66 kg weight category.

There, he met former European champion Vazha Margvelashvili of Georgia, losing by ippon and turning to compete at the repechage for a chance to win a bronze medal.

[46] Shmailov gave a special thanks to team coach Oren Smadja, "who made the really difficult decision to come here" just a few weeks after his son Omer was killed while fighting with the IDF in Gaza.