The trust, which runs St Richard’s and Worthing and Southlands hospitals, received the award from the CHKS based on a 21-point list of criteria including health outcomes, efficiency, patient experience and quality of care.
Independent provider of healthcare intelligence and quality improvement services CHKS chose the winners from 135 candidates.
The criteria this year included the rate of emergency readmission to hospital, reported rates of hospital-acquired infections, an inpatient survey and an A&E survey.
Trust chief executive Marianne Griffiths said: “This is a well-deserved accolade for our staff and reflects the hard work and commitment to continuously improve our services.
“Our aim is always to try to make sure our patients receive top-quality care, and staff right across the trust can be very proud of this award.”