Baldwin of Luxembourg (German: Balduin von Luxemburg) (c. 1285 - 21 January 1354) was the Archbishop of Trier from 1307 until 1354, (as Baldwin III) the administrator of the Archbishopric of Mainz from 1328 until 1336, and the administrator of the Bishoprics of Worms and Speyer from 1331 until 1337. Baldwin is considered to be the greatest of all the Prince-Bishops of Trier.

Baldwin was born in Luxembourg as the youngest son of Count Henry VI, and as the youngest son it was decided he would be a churchman. Baldwin studied theology in Paris, as the counts of Luxembourg maintained a good relationship with the Capetian kings. In 1307 he was elected the Archbishop of Trier, and was confirmed the following year by Pope Clemens V. Through skilled diplomacy, he ensured his brother, Count Henry VII, was elected King of Germany, and from 1310 until 1313 travelled with him in Italy where Henry was crowned the first Holy Roman Emperor in a Century.

However Henry caught malaria in 1313 he died in Siena on August 24th. At the next Imperial election, Baldwin then supported Duke Louis IV of Upper Bavaria, who was elected. Baldwin later disassociated himself with Louis. Baldwin built Balduinstein in 1319, which greatly increased the already formidable power of the archdiocese, and he alienated much of the aristocracy of the Rhineland. In 1328 he was lured to Starkenburg by Loretta of Sponheim, who only released him after the payment and granting of concessions to the Sponheims. Later in 1328 he was elected Archbishop of Mainz, however the Pope instead appointed Henry of Virneburg. Despite that, Baldwin continued to administer that archdiocese with the support of the cathedral chapter. He only ceased in 1336 when the judgement of the curie of Avignon went against him. In 1331 he also became the administer of the dioceses of Speyer and Worms, which granted him a large and powerful territory until he was restricted to Trier in 1337.

Baldwin developed the archdiocese of Trier markedly. He built the Balduinbrücke over the Mosel in Coblenz in 1344. Also in Coblenz he constructed a castle which in later times became the residence of the archbishops of Trier. He also allowed all documents and records of Trier to be recorded and copied, which became called the Balduineum and was housed in Coblenz as a basis of administration. Baldwin was also aggressive and militaristic in his enlargement of the archdiocese. He connected all of the territories of the archdiocese, and he had no qualms about using force to obtain his means, such as in the Eltzer Feud.

Baldwin died in a cell of the Abbey of the Karthäuser in Trier in 1354, and was buried in the west choir of the cathedral in Trier.

Preceded by:

Baldwin of Luxembourg

Succeeded by:

Theodoric III of Nassau-Wiesbaden-Idstein Archbishop of Trier
1307 - 1354
Bohemond II of Saarbrücken
Matthias of Bucheck Administrator of Mainz
1328 - 1336
Henry III of Virneburg