The article presents Hans Urs von Balthasar’s theological ideas on Vatican II. The Swiss theologian was an attentive spectator of the council, even though he was not physically present at the ecclesial event. His ecumenical interventions were made before, during and after the Council, as is presented in the following parts of the article. First of all, a common theme with Vatican II is the attention to Scripture and how he integrates his patristic knowledge into this interpretative framework. Secondly, the Swiss theologian proposed an incarnationist vision of earthly realities and insisted on the missionary dimension of the Church, as well as the importance of the laity and the centrality of the constitution Lumen Gentium among the texts of Vatican II. Finally, in addition to a common Christocentrism, Balthasar appreciates in the conciliar texts important advances with regard to Mariology and religious freedom.