'The Flying Scotsman' averaged 99.7 against Poland's Ratajski at Halle 39 en route to claiming the 51st title of his career.
Anderson started the day with a comfortable win over Jamie Hughes before fending off Jelle Klaasen - a late replacement into the tournament.
The world number 22 then claimed solid victories over Luke Humphries, Dimitri Van den Bergh and Gian van Veen, who defeated Northern Irish talent Josh Rock in round one.
Anderson then toppled world number four Gerwyn Price 7-3 to book his place in the final.
Ratajski was largely untroubled en route to the final, downing all of Richie Burnett, Ryan Meikle and Boris Krcmar in simple fashion in the first three rounds.
The 46-year-old faced his biggest challenges of the day which he completed via a last-leg shootout, knocking out both of Dave Chisnall and Brandan Dolan.
Ratajski then breezed past Germany native Ricardo Pietreczko in the semi-finals before falling to Anderson.