The longest-serving pope with a fully verified reign was Pope Pius IX , who led the Catholic Church for 31 years, 7 months, and 23 days, from 1846 to 1878.

Quick Scoop

So, who was the “longest” pope?

If you mean the longest time in office , not height or age, the top answer in documented history is:

  • Pope Pius IX (Giovanni Maria Mastai-Ferretti)
    • Reign: 1846–1878.
* Duration: About 31 years, 7 months, 23 days.

* He is widely recognized as the **longest-reigning confirmed pope** in Catholic history.

You will sometimes see Saint Peter listed as “number one” with around 34 years as bishop of Rome, but this is based on tradition rather than the same kind of precise, day-counted historical records used for later popes. For that reason, many modern lists treat Pius IX as the longest verifiable papacy.

A bit of context (in short)

  • Saint Peter
    • Traditionally: c. 30–64 or 67 AD (about 34–37 years).
* Status: Foundational figure, but dates are approximate and not “verified” in the modern historical sense.
  • Pope Pius IX
    • Historically documented reign with exact dates and day counts.
* Holds the record for the **longest clearly documented pontificate**.

So if your question is “who was the longest pope?” in the usual sense of longest time as pope , the best historically grounded answer is Pope Pius IX. TL;DR:

  • Traditional longest: Saint Peter (about 34 years, not precisely documented).
  • Longest verified reign: Pope Pius IX (31 years, 7 months, 23 days) — this is the answer most historians give.

Information gathered from public forums or data available on the internet and portrayed here.