The incidence of small bowel lymphoma (SBL) is increasing worldwide. In contrast to resectable SBL, the treatment of unresectable SBL is still contentious. Here, we report a case of unresectable SBL that was treated by laparoscopic exclusion of the affected intestine before systemic chemotherapy was administered. An 84-year-old man was diagnosed with primary SBL involving extranodal dissemination. The patient received prophylactic surgery, namely exclusion of the affected intestine. This therapy diminishes well-known and life-threatening complications, such as perforation, bleeding, and obstruction, which may still occur after chemotherapy, and it makes the administration of chemotherapy safer. In addition, the surgery provides easy access for direct endoscopic observation and biopsy, which are otherwise difficult to perform. Follow-up after two courses of chemotherapy showed that the patient had achieved complete remission. In conclusion, the procedure described here may be an effective strategy for unresectable SBL.