In 2017, Kostadinov created history by becoming the youngest Mayor in Europe, managing Strumica Municipality for 10 months. Starting from 2017, he continued making impact at the National level as an MP at the Macedonian Parliament, contributing to important historical decisions, particularly related to Macedonia's Euro-Atlantic future.
Motivated by his belief in Regional development and European principles, Kostadinov was elected as Strumica's Mayor in 2021. Since taking over the Mayor’s Office in October 2021, he has actively worked to drive progress in the Municipality of Strumica.
Kostadinov's tenure has seen notable achievements in economic development, infrastructure enhancement, and community welfare. His dedicated leadership underscores his commitment to the people and the future of Strumica, making him a dynamic and proactive force in local governance.
Led by the premise "From the heart for Strumica | Од Срце за Струмица", Kostadinov creates policies for an inclusive and multicultural Municipality, perhaps one of the few in Macedonia. In this manner, Strumica Municipality's year-round cultural calendar reflects the commitment to nurturing and promoting the arts.
"Strumica Carnival", "International Art Colony", "International Festival of Chamber Theater: Risto Shiskov", "Festival of Aphorism and Caricature", "International Film Festival AsterFest", "Strumica Open Fest", "Festival of Traditional Folk Songs and Serenades: Under the Towers of Strumica"; "Get EXITed" and some more, are the events that provide a platform for local and international artists to showcase their talents and contribute to the cultural richness of Strumica, making it a City that truly comes alive with the spirit of creativity and tradition.
In addition, in the long-term strategy for progress and development of the Municipality, one of the main focuses is dedicated to Regional development of Strumica, according to the principle of equidistance. In this direction, the international cooperation achieved with Greece and Bulgaria dominates in several fields. The Municipality of Strumica keeps permanent social relations with these neighboring Countries, while showing remarkable results.