The Bahia Palace (Arabic: قصر الباهية) is a mid to late 19th-century palace in Marrakesh, Morocco. The palace was first begun by Si Musa, grand vizier under the Alawi sultan Muhammad ibn Abd al-Rahman, in the 1860s. It was expanded by his son Si Ba Ahmed ibn Musa, grand vizier of Sultan Moulay Abdelaziz, between 1894 and 1900. Today it is a well-known historic monument and tourist attraction in the city.

The palace has an irregular layout comprising around 150 rooms organized around multiple internal courtyards and riad gardens. It is most notable for its decoration, particularly its painted wood ceilings, along with sculpted stucco and zellij tilework. The original grounds of the palace also encompassed a wider area with gardens, parks, stables, a mosque, and other annexes.

Si Musa was descended from a family of black slaves which served the Moroccan makhzen (royal government) and reached the highest offices in the country. He was first hajib (similar to a chamberlain) then grand vizier under Muhammad ibn Abd al-Rahman, who reigned from 1859 to 1873. Construction of the palace took place in the 1860s.^{[better source needed]}

Among the existing parts of the palace today, the "Grand Riad" or large riad garden and its adjoining rooms in the northern part of the palace date from Si Musa's time and are also consequently known as the Dar Si Moussa. The two chambers on the east and west sides of the garden contain an inscription which dates their construction to 1866–7.

Ahmad ibn Musa, known also as Ba Ahmed, was hajib to Sultan Moulay Hassan and, upon the latter's death, ensured his son Abdelaziz's accession to the throne in 1894, earning him a promotion to grand vizier. As Abdelaziz was only sixteen, Ba Ahmed became the effective ruler of Morocco until his own death from disease in 1900. During his tenure, he was also supported by his two brothers, Si Sa'id and Idris (who died with him in 1900).

He progressively expanded his father's palace throughout these years as grand vizier (1894–1900), adding to it piece by piece as new land became available for purchase. His brother Si Sa'id built his own palace north of here during this time, the Dar Si Said, which today serves as a museum.

Ba Ahmed was responsible for constructing most of the Bahia Palace's southern parts, which include various smaller courtyards and riad gardens. The marble-paved Grand Courtyard, one of the largest spaces in the palace today, is dated to 1896–7, during Ba Ahmed's tenure. On the east side of this palace complex, he created a vast private park and garden, complete with a central water basin. It could be accessed from the palace via a bridge over the adjacent street. The architect was a man named Muhammad ibn Makki al-Misfiwi, originally from Safi, who was born in 1857 and died in 1926. The palace's growth overtook much of the previously existing neighbourhood north of the Mellah and resulted in major changes in the local street layout. The growing palace housed Ba Ahmed's servants (including his own slaves) and his harem (private family residence). The name al-Bahia (Arabic: الباهية), meaning "the Brilliant", was reportedly the name of his favourite wife. The entire palace was built on one level, possibly as Ba Ahmed's own physique (which was described as stout and obese) made it more difficult for him to go up and down stairs.

After Ba Ahmed's death in 1900, his palace became royal property. Mere hours after his death, Sultan Abdelaziz (who subsequently took full power over the country) reportedly ordered the palace to be looted for valuable items. In 1908, Madani el-Glaoui, brother of Thami el-Glaoui, took control of the palace and subsequently used it to entertain foreign guests. He added an upper floor for the first time to some parts of the palace.