There will not be a ninth season of Foyle's War. Eleventh Hour Films and Acorn Productions announced that the final episode aired on January 18, 2015 according to ITV.
Show writer and creator, Anthony Horowitz, said he felt that he had written all there was to write in the fifteen plus years that he has worked on the Foyle's War project. He also acknowledged that the last season had some of the best episodes of the entire series. This last season will be available exclusively from Acorn Online, according to the Acorn Media Group. There is no word on whether or not PBS will be airing the last season.