The Chair of Saint Peter (Latin: Cathedra Petri), also known as the Throne of Saint Peter, is a relic conserved in St. Peter's Basilica in Vatican City. The relic is a wooden throne that tradition claims belonged to the Apostle Saint Peter, the leader of the Early Christians in Rome and first Pope, and which he used as Bishop of Rome. The relic is enclosed in a sculpted gilt bronze casing designed by Gian Lorenzo Bernini and constructed between 1647 and 1653. In 2012, Pope Benedict XVI described the chair as "a symbol of the special mission of Peter and his Successors to tend Christ's flock, keeping it united in faith and in charity."

The wooden throne was a gift from Emperor of the Romans Charles the Bald to Pope John VIII in 875. It has been studied many times over the years, most recently between 1968 and 1974. The study concluded that it was not a double, but a single chair, with a covering, and that the oldest parts are from the 6th century. The Chair of Saint Peter is the second altar within the church, with the first one being the one under St. Peter's Baldachin. It stands to remind visitors of the Catholic Church's authority.

In January 2024, the Vatican Museums, Fabbrica di San Pietro, the Commission for the Protection of Monuments and other Vatican institutions announced a restoration campaign of the baldachin over the high altar and adjacent Altar of the Chair that was expected to cost approximately €700,000 and was funded by a gift from the Knights of Columbus. This was the first major work done in these areas since 1758.

On 27 October 2024, the newly restored chair was shown in public for the first time since 1867, on a decision by Pope Francis. After the concluding Mass of the Synod on Synodality, it was centered in front of the baldachin. By 28 October, the chair was in front of the right front pillar. The chair was due to be on display until 8 December 2024 but was returned to the reliquary on 26 November 2024.

The relic itself is described as an oaken chair damaged by cuts and worms. The chair has metal rings attached to each side, allowing use as a sedia gestatoria. The back and front of the chair are trimmed with carved ivory. This description comes from 1867, when the relic was photographed and displayed for veneration.

The reliquary, like many of the medieval period, takes the form of the relic it protects, i.e. the form of a chair. Symbolically, the chair Bernini designed had no earthly counterpart in actual contemporary furnishings. It is formed entirely of scrolling members, enclosing a coved panel where the upholstery pattern is rendered as a low relief of Christ instructing Peter to tend to his sheep. Large angelic figures flank an openwork panel beneath a highly realistic bronze seat cushion, vividly empty: the relic is encased within.

The cathedra is lofted on splayed scrolling bars that appear to be effortlessly supported by four over-lifesize bronze Doctors of the Church: Western doctors Saint Ambrose and Saint Augustine of Hippo on the outsides, wearing miters, and Eastern doctors Saint John Chrysostom and Saint Athanasius on the insides, both bare-headed. The cathedra appears to hover over the altar in the basilica's apse, lit by a central tinted window through which light streams, illuminating the gilded glory of sunrays and sculpted clouds that surrounds the window. Like Bernini's Ecstasy of Saint Theresa, this is a definitive fusion of the Baroque arts, unifying sculpture and richly polychrome architecture and manipulating effects of light.

Above, on the golden background of the frieze, is the Latin inscription: "O Pastor Ecclesiae, tu omnes Christi pascis agnos et oves" ('O Shepherd of the Church, you feed all Christ's lambs and sheep'). On the right is the same writing in Greek, "ΣΥ ΒΟΣΚΕΙΣ ΤΑ ΑΡΝΙΑ, ΣΥ ΠΟΙΜΑΙΝΕΙΣ ΤΑ ΠΡΟΒΑΤΙΑ ΧΡΙΣΤΟΥ". Behind the altar is placed Bernini's monument enclosing the wooden chair, both of which are seen as symbolic of the authority of the Bishop of Rome as Vicar of Christ and successor of Saint Peter.