Following his career with the youth team of TSV 1860 Munich that begun in 1970, Seelmann would be promoted to the professional squad for the 1971–72 season. In his first professional year in the former second tier Regionalliga Süd, he played 32 games out of a possible 36 and scored one goal in the home game against KSV Hessen Kassel which ended 1-1. With 1860, Seelmann finished third in each of the last three seasons of the former Regionalliga from the 1971–72 season to the 1973–74 season, missing out the Bundesliga promotion playoffs against Kickers Offenbach, Bayern Hof, SV Darmstadt 98, Karlsruher SC, FC Augsburg and 1. FC Nürnberg.[1] Even with the arrival of players such as Ferdinand Keller and Hans-Joachim Weller from Hannover 96 in his second season, the team would ultimately be unable to harmonize and would stay within the second division of German football.[2][3]
Seelmann remained loyal to the Löwen for a total of five seasons until the end of the 1975–76 season. This was due to the club repeatedly missing promotion to the Bundesliga with the club being forced to take rigorous austerity measures due to increasing debt as Seelmann went to amateur league club Wormatia Worms. Seelmann, who had been promoted to team captain throughout his career, played a total of 132 games in the white and blue jersey and from 1974 to 1976 in the 2. Bundesliga, he played 43 games with one goal as he would score four goals for this entire career.[1][4][5]
In their first season without Seelmann in 1976–77 season, of all things, the Munich Löwen managed to get promoted to the Bundesliga. Seelmann was present at the all-important 2–0 victory of his former team against Arminia Bielefeld in Frankfurt's Waldstadion. Despite betting 500 German marks on their victory on that day, he was internally heartbroken that he wasn't there with the Löwen to oversee his club be promoted to the top-flight of German football with the rest of his teammates.[1][5] His new club of Wormatia Worms would also get promoted just a few days later following their victories against Borussia Neunkirchen and TuS Neuendorf in the promotion playoffs in the southwest with the club heading into the 2. Bundesliga Süd while his former club had just left for the Bundesliga.[1]
But because the Munich team was relegated after just one season and Wormatia Worms stayed in the league, Seelmann faced his old comrades on the pitch for the first time in the 1978–79 2. Bundesliga. When 1860 Munich was promoted to the Bundesliga again at the end of the season, Seelmann returned to his old club after 60 games and three goals from 1977 to 1979 in the 2. Bundesliga for Worms[4] but he wouldn't make a single appearance and left the club before the 1980–81 season for SpVgg Fürth. He played a total of 87 games for the Shamrocks in three seasons in which he scored two goals before ending his active career in 1987 with SV Seukendorf.[1][4]