The Chapel was one of the first sites built by Mateus Vicente de Oliveira, the first architect to work on Queluz. Containing but a single nave, whilst differentiating between the areas of the main chapel, with its octagonal layout and choir stalls. Access to the chapel and the upper stalls was made via a staircase leading out of the Lantern Room. Here, from behind a trellis, the Royal Family was able to attend religious services without being visible to other members of the congregation.
The gold-leafed carving of Rococo inspiration, carried out under the supervision of Silvestre de Faria Lobo, was already completed by 1752. The chapel displays influences from the Chapel of St. John the Baptist in the São Roque Church and also became a point of reference for religious buildings throughout the Lisbon region. The main chapel's altarpiece representing Our Lady of Conception, patron saint of Queluz, was the work of André Gonçalves, and completed in 1752. The lateral altar panel representing the imprisoning of Saint Peter and Saint Paul was also his work whilst the portrayal of Saint Francis of Paola was painted by Pedro Alexandrino de Carvalho. The ceiling painting, evoking the Virgin, also dates to 1752.
The composers David Peres, Scarlatti and João Cordeiro da Silva conducted their works on the carved and gold-leafed choir, and during the Palace's golden era many Italian singers performed there. In 1802, Marcos Portugal composed two psalms for the Royal Chapel of Queluz.