This volume contains the post-proceedings of the 9th Doctoral Workshop on Mathematical and Engineering Methods in Computer Science, MEMICS 2014, held in Telc, Czech Republic, in October 2014. The 13 thoroughly revised papers were carefully selected out of 28 submissions and are presented together with 4 invited papers. The topics covered by the papers include: algorithms, logic, and games; high performance computing; computer aided analysis, verification, and testing; hardware design and diagnostics; computer graphics and image processing; and artificial intelligence and natural language processing.