Smilgevičius studied economics at the University of Königsberg and at the University of Berlin, graduating in Berlin in 1899. He then worked for the Russian Ministry of Agriculture in St. Petersburg for three years. He lived for a time in Warsaw, where he worked in private industry, and then moved to Vilnius, where he co-founded and directed the agricultural machinery firm Vilija.
During the Interwar period, he pursued various private enterprises, and contributed to several economic organizations. Many of his efforts were centered on improving the family estate in Užventis; he sponsored the construction of a brickyard, sawmill, and distillery there. He died in Kaunas in 1942.