Braniewo ([braˈɲɛvɔ]) (German: Braunsberg in Ostpreußen) is a town in northern Poland, in Warmia, in the Warmian-Masurian Voivodeship, with a population of 16,907 as of June 2021. It is the capital of Braniewo County.

Founded in the Middle Ages, Braniewo is the oldest city in Warmia, and currently the second largest (after Olsztyn), and was its first capital until 1340. From the late medieval period, it prospered from international trade, and in the early modern period, it was a significant center of higher education in Poland, called the "Athens of the North." Additionaly, since the 16th century Braniewo is a noted center for brewing. The town features heritage sites in a variety of styles, including Gothic, Baroque, Neoclassical and Gothic Revival. Braniewo hosts a garrison of the Polish Armed Forces and is a member of Cittaslow.

Braniewo lies on the Pasłęka River about 5 km (3 mi) from the Vistula Lagoon, about 35 km (22 mi) northeast of Elbląg and 55 km (34 mi) southwest of Kaliningrad (Polish: Królewiec). The Polish border with Russia's Kaliningrad Oblast lies 6 km (4 mi) north, and may be reached from Braniewo via National road 54.

According to the German geographer Johann Friedrich Goldbeck (1748–1812), the town originally was named Brunsberg after Bruno von Schauenburg (1205–1281), bishop of Olomouc in Moravia, who accompanied King Ottokar II of Bohemia in 1254 and 1267 when the latter participated in the crusade of the Teutonic Knights against the Old Prussians. It has also been suggested that the name Braunsberg might stem from Brusebergue ("camp of the Prussians"), but this notion is not documented.

In 1243, the settlement and the surrounding region of Warmia was given by the Teutonic Order to the newly created Bishopric of Warmia, whose bishop built his cathedral in the town and made it his chief residence. The city was granted town privileges based on those of Lübeck in 1254, but in 1261 was destroyed and depopulated during the second of the Prussian Uprisings. It was rebuilt in a new location in 1273 and settled by colonists from Lübeck. In 1284, it was given a new town charter, again based on that of Lübeck. However, the next bishop, Heinrich Fleming (1278–1300), transferred the chapter from Braunsberg to Frauenburg (now Frombork).

In 1296, a Franciscan abbey was built, and in 1342, a "new town" was added. As the most important trading and harbor city in Warmia, the town prospered as member of the Hanseatic League, which it remained until 1608. The town maintained trade contacts with England, Sweden, Denmark, the Netherlands, and Livonia.

In 1440, the town was one of the founding members of the Prussian Confederation, which opposed Teutonic rule, and upon the request of which King Casimir IV Jagiellon incorporated the territory to the Kingdom of Poland in 1454. The town pledged allegiance to the Polish King and recognized his rule in March 1454 in Kraków. After the subsequent Thirteen Years' War, the Teutonic Knights renounced any claims to the town in the Second Peace of Thorn in 1466. Administratively, it was part of the Prince-Bishopric of Warmia in the new autonomous province of Royal Prussia, later on also in the Greater Poland Province.

After the secularization of the Teutonic Order in 1525, a large part of its residents converted to Lutheran Protestantism. Duke Albert, who had been grand master of the Order, sought to unite Warmia with Ducal Prussia (a nearby vassal state of Poland), causing the Catholics of the town to swear allegiance to the king of Poland in return for aid against Protestant Prussia. In 1526 a Polish royal commission released Braunsberg burghers from the oath to the Polish king and handed the town back to Prince-Bishop Mauritius Ferber. However, just like the entire area of Warmia, Braunsberg swore allegiance to the Prince-Bishops of Warmia. Additionally, it had to denounce all Lutheran teachings and hand over Lutheran writings. Thereafter Warmia remained predominantly Roman Catholic (even after the Partitions of Poland, when it became part of Prussia in 1772).