The aim of the present study was to model indoor TV/screen viewing and a series of adult health conditions and cognitive performance in a country-wide, population-based setting in recent years. Data was retrieved from Health Survey for England, 2012. Information on demographics, lifestyle factors, self-reported health conditions, and TV and/or screen watching hours in adults was collected by household interviews. Chi-square test and survey-weighted logistic and multi-nominal modeling were performed. Of 8114 English adults aged 18–98, 4138 people (51.1 %) watched TV and/or screen daily for 2 h or more on average. Two thousand five-hundred people (30.9 %) watched for 3 h or more. TV and/or screening watching for 2+ hours was associated with endocrine or metabolic disorders, diabetes, mental disorders (including poor scores in General Health Questionnaire and Warwick-Edinburgh Mental Well-being Scale), nervous system disorders, eye complaints, circulatory system disorders, respiratory system disorders, musculoskeletal system disorders, and self-rated health. TV and/or screen watching for 3+ hours was associated with digestive disorders and clotting disorder. TV and/or screen watching for 5+ hours was associated with cancer. TV and/or screen watching for 6+, 8+, or 11+ hours was associated with bladder disease, genito-urinary system disorders or bowel disease, respectively. There were no risk associations (within 20 h) found with ear complaints, infectious disease, and blood system disorders. Future educational and public health programs minimizing TV and/or screen viewing in order to protect from physical inactivity and X-radiation might be needed while research on the combined effect of physical inactivity and X-radiation should be explored.