Raised to the rank of Privy Chamberlain of His Holiness on 18 May 1911, Massimi was made auditor (29 November 1915), pro-dean (19 February 1924), and dean (1 May 1926) of the Roman Rota.
Massimi was promoted to a high-ranking position as Privy Chamberlain of His Holiness on 18 May 1911. He later took on various administrative roles, including auditor (29 November 1915), pro-dean (19 February 1924), and dean (1 May 1926) of the Roman Rota.