Stenotrophomonas maltophilia is a Gram-negative opportunistic bacterium that is increasingly being associated with infections. Here, we report the complete genome of the S. maltophilia myophage Marzo, with a 159,384-bp genome encoding 268 proteins, 23 tRNAs, and 1 transfer-messenger RNA. Marzo is closely related to S. maltophilia phages IME-SM1 and Mendera.