This book constitutes the proceedings of the 27th International Working Conference on Requirements Engineering - Foundation for Software Quality, REFSQ 2021, which was due to be held in Essen, Germany, in April 2021. Due to the COVID-19 pandemic the conference was held virtually in April 2021. The special focus of this year`s REFSQ 2021 conference are contributions emphasizing the importance of human values, such as privacy and fairness, when designing software-intensive systems as well as the challenges that intelligent and autonomous systems pose due to the tight interplay with humans.