The trust which runs SE1's two NHS hospitals has been rated as 'good' by the Care Quality Commission.
Inspectors visited the two hospitals in September last year and have since carried out follow-up visits.
The full reports are available on the CQC website.
The chief inspector of hospitals, Professor Sir Mike Richards, said: "Guy's and St Thomas' sets out to provide world class clinical care, education and research that improves the health of the local community and of the wider population – and if you ask their patients, the vast majority would tell you that is their experience.
"Throughout our inspection we found evidence of clear supportive leadership and staff who are highly committed to the trust, delivering high quality, compassionate, patient care. Patients were positive about the care they received and felt staff treated them with dignity and respect."
Urgent and emergency services at St Thomas' Hospital were rated as 'outstanding', as was the Evelina Children's Hospital.
Sir Mike sounded a note of caution over the high level of 'never incidents' (serious errors such as wrong-site surgery) at the hospitals.
He added: "Staff knew how to report incidents, but there was only limited learning from Never events across directorates. I note that the trust has not been meeting the 62-day target on access to cancer treatment for some time.
"I know that the trust is facing increasing demand on its services, and we will continue to monitor its performance in these challenging times."
Responding to the CQC report, Amanda Pritchard, chief executive of Guy's and St Thomas', said: "I welcome this report which paints a very positive picture of the compassion and dedication of our staff to deliver high quality care to patients.
"I am delighted that the CQC has highlighted so many areas of excellent practice throughout the trust and has rated both our children's and emergency services as outstanding.
"The CQC report also highlights areas for improvement and I look forward to working with our staff, patients and local stakeholders to tackle these together in the weeks and months ahead."