Service innovation offers service firms an opportunity to strategically renew their brands in a continuum that fosters increased interactions between the firm, its customers and other stakeholders. Essentially, the many benefits service innovation concept offers businesses, makes it quite germane for businesses seeking to compete favourably in a fast paced technologically and knowledge based economy we live in. This study therefore conducts a systematic review on Service Innovation in the Service Sector (SISS) with a view to develop a quantitative summary of the field and provide a guide for future researchers. The Systematic Quantitative Assessment Technique (SQAT) developed by Australian researchers Catherine Pickering and Jason Anthony Bryn in 2013, was used to identify and review 94 peer- reviewed service innovation articles within 2008-2017 from six high quality academic databases. The findings of this study is a new study in SISS research with the primary focus of SISS articles on seven themes. 12 out of the 94 papers were found to have taken place in the UK, with China and Taiwan sharing 9 papers each and 8 papers only in Malaysia. All the 94 SISS articles adopted a single research method with 28 papers adopting the use of questionnaire. Also, the study revealed no literatures on SISS exists in Nigeria. Directions for future research were suggested and appropriate conclusions drawn. The findings of this study would look to guide policy planners and researchers alike on the course of current SISS research. This will in turn inform their choice aspects of SISS literatures seeking urgent research. This study is a new addition to existing literature and a novel quantitative summary in the area of service innovation within the service context.