 Heinrich succeeded his brother Henry IX as Count of Reuss-Obergreiz in 1723.After the death of Count Henry III Reuss-Untergreiz, in 1768, including the city of Untergreiz passed to the domains of the Heinrich XI and he was able to gather these possessions and guaranteed the line of succession.On 12 May 1778 Heinrich was elevated to Prince () by the Holy Roman Emperor Joseph II.