On 27 May 927, Simeon died of heart failure in his palace in Preslav. Byzantine chroniclers tie his death to a legend, according to which Romanos decapitated a statue which was Simeon's inanimate double, and he died at that very hour. Tsar Simeon I has remained among the most highly valued Bulgarian historical figures.

Peter, Simeon's son, negotiated a peace treaty with the Byzantine government. The Byzantine Emperor Romanos I Lakapenos eagerly accepted the proposal for peace and arranged for a diplomatic marriage between his granddaughter Maria and the Bulgarian monarch. In October 927 Peter arrived near Constantinople to meet Romanos and signed the peace treaty, marrying Maria on 8 November in the church of the Zoödochos Pege. To signify the new era in Bulgaro-Byzantine relations, the princess was renamed Eirene ("peace"). The treaty of 927 actually represents the fruit of Simeon's military successes and diplomatic initiatives, ably continued by his son's government. Peace was obtained with the frontiers restored to those defined in treaties of 897 and 904. The Byzantines recognised the Bulgarian monarch's title of emperor (basileus, tsar) and the autocephalus status of the Bulgarian patriarchate, while the payment of an annual tribute to Bulgaria by the Byzantine Empire was renewed. Peter of Bulgaria would rule peacefully for 42 years.