The frescoes in the sanctuary are attributed to Carloni Brothers, born in the Intelvi Valley. The triumphal arches, the walls of the sanctuary, the vaults, and the apse were decorated on multiple occasions. The triumphal arch displays a precious fresco depicting the "Christ in Glory," attributed to Tagliaferri, a renowned painter from Valvarrone, created at the end of the 19th century. From the same period comes the second triumphal arch with angels adoring the cross; notable is the elegant festoon of branches and leaves with fruits, as well as the central finishing "in the form of a cloud" of the arch.
The fresco is quite different from the rest of the decorative scheme, which opens grandiosely into two illusory colonnaded environments flanking a further illusory altarpiece depicting Saint Bernardino, portrayed in ascetic form indicating the trigram, with personifications of the virtues of strength invoking dialogue and prudence with the serpent. On the sides of the fake altarpiece, in two separated environments, we find Faith and Charity with their classical symbols. At the top, the semi-dome is crowned by a balustrade of another illusory environment, rich in fruits and flowers. In the lateral panels of the sanctuary, two scenes of Jacob's dream and struggle are painted, both referrable to strength and to the ladder of virtues that Bernardino managed to ascend towards glory, as depicted in the barrel vault fresco showing Saint Bernardino in the glory of the Paradise, enriched by decorative elements of fruits with festoons of leaves and branches on a polychrome faux marble background.
The fresco on the elliptical vault of the apse, overlooking a precious walnut wood choir that runs along the entire apse, shows figures of angels adoring the Holy Spirit's Dove, perhaps attributable to Tagliaferri. Notorious is the splendid fresco with a faux marble balcony, decorating the culminating part of the apse. A magnificent example of trompe-l'œil decoration.