It was built at the end of the 14th century on the southern slope of the hill of the primitive Vitoria, outside its walls and the gate of San Bartolomé. It probably occupies the same site as the juradera church, also dedicated to San Miguel, which is mentioned and located at the gates of the town in the document of the founding charter granted by the Navarrese King Sancho VI the Wise in 1181. The church overlooks calle Mateo Moraza and dominates the squares of the Virgen Blanca and General Loma, vital centres of the town, and its Gothic style contrasts with the group of Neoclassical constructions that run along its base.

It is a rectangular church with three unequal naves of four bays, an octagonal chancel and two side apse chapels. On the left wall there are three chapels and a two-storey room. On the right wall there are four chapels, the main door with its portico and the sacristy. The vaults have complex ribbed vaulting, particularly the one that covers the main chapel, with ribs and keystones painted in gold, as well as the ogives of the arches, and whitewashed plementeries, like the wall panels that separate the naves, over the former arches.

In the gable, almost covered by terraced houses and next to the tower, there is another access to the church, today out of use, the so-called Puerta del Solar, which is accessed by a narrow staircase from Calle Correría. On the outside of the semi-hexagonal apse, facing the Palace of Villa Suso and the Plaza del Machete, you can still see the latticed niche that held the machete on which the trustee swore, before the people, to look after the interests of the city.

The building of San Miguel is made up of different construction periods. Of the oldest part, Gothic from the end of the 14th century to the beginning of the 15th century, the supports of the first section and the partially mutilated main doorway remain, the best preserved part of which is the tympanum arranged in three bands, the two lower ones centred on traditional scenes of Saint Michael and the upper one showing the glorious manifestation of the Father giving Christ the Redeemer to the world, flanked by the Virgin Mary and Saint John praying. Later in the 15th century and within the so-called Basque Gothic style, the round columns with collared capitals, the vaults and the aforementioned Puerta del Solar were erected.

Plateresque, from the early 16th century, are the choir, the portico and a sepulchral arch in the Main Chapel, with the mausoleum of the Arriaga family. The Main Chapel itself dates from the mid-16th century. At the end of this century the tower was built, a prismatic structure topped by a spire with a Baroque hexagonal lantern, from the 18th century, the work of Valerio de Ascorbe and very similar to that of the nearby church of San Pedro Apóstol, erected by the same artist.

The most remarkable part of the interior is undoubtedly the main altarpiece, a magnificent early Baroque work by Gregorio Fernández, who made it between 1624 and 1632. The gilded masonry of three sections and five aisles is presided over by an image of La Purísima with her mantle draped over her shoulders and her hands joined in the centre, in the style of the Castilian Immaculate Conception of the first half of the 17th century. In the upper sections there are scenes of Saint Michael flanking the image of the patron saint and the sculptural group of the Calvary. Prior to this Baroque altarpiece there was a Gothic one and another Renaissance one contracted by Lope de Larrea and Juan de Anchieta, which was never finished. Two reliefs from this unfinished altarpiece are preserved in the sacristy.

The current portico dates from the 16th century and is superimposed on the previous structure. Covered by a late Gothic star-shaped ribbed vault, it is accessed by a wide staircase and through two large, slightly pointed twin arches. The complex opens onto the square of the Virgen Blanca, patron saint of the city of Vitoria, whose image is housed in a sturdy marble niche between the two access arches. The niche dates from the 18th century and the carving is a polychrome Gothic stone niche with the Virgin in majesty holding the child.