The wildcard produced a fine performance on the clay in Hamburg to earn a 6-3 4-6 6-2 success against his Finnish opponent.
Kamke, ranked 25 places below Nieminen at number 83, had lost all of the four previous encounters between the two and, despite taking the first set, looked set for another defeat after the Finn's strong serving saw him level matters.
But Kamke, who claimed five breaks of serve in the match, recovered his composure to take the third.
The German wildcard was not the only surprise winner on the first day of the ATP 500 tournament, Frenchman Benoit Paire coming through in a tie-break after two lopsided sets to beat 2010 champion Andrey Golubev of Kazakhstan 1-6 6-1 7-6 (7-4).
Triumph for Paire snapped a run of four consecutive first-round exits on Tour.
There was better fortune for Golubev's compatriot Mikhail Kukushkin as the highest-ranked player on day one eased to a 6-2 6-2 victory against Turkish qualifier Marsel Ilhan.
Meanwhile, Kenny De Schepper could not replicate the exploits of fellow Frenchman Paire, losing 6-3 6-2 to Serbian Dusan Lajovic.
But perhaps the most impressive winners of the day were Austrian Dominic Thiem and Spaniard Daniel Gimeno-Traver.
Thiem won 20 of his 21 first service points on his way to delivering a bagel in his 7-5 6-0 hammering of Jiri Vesely, while qualifier Gimeno-Traver cruised through by beating Russian Teymuraz Gabashvili, a player 29 places above him in the rankings, 6-2 6-3.
Dustin Brown did not drop serve as he provided more home success with a 7-6 (7-5) 6-3 triumph over Spain's Pablo Carreno-Busta, however, compatriot Jan-Lennard Struff lost 1-6 7-5 6-2 to qualifier Filip Krajinovic.
Elsewhere in the draw there were straight-sets wins for Gastao Elias and Pablo Andujar against Albert Montanes and Mate Delic respecitvely.