Velichkov made his official debut for Botev in a match against CSKA Sofia on 1 October 2006. He played for 90 minutes. The result of the match was 1–0 with win for Botev. On 2 September 2007. he scored his first goal for Botev against Lokomotiv Sofia. He scored goal in 66th minute for 2–1 for Botev. The result of the match was 2–2.