Siegfried II of Eppstein (c. 1165 - 9 September 1230) was the Archbishop of Mainz from 1200 until 1230.

Siegfried was the second son of Count Gerard I of Eppstein. He was made the provost of St Gangolph in Mainz in 1189, St Martin in Worms in 1194, and St Peter in Mainz in 1196. Following the death of the Archbishop Conrad I of Wittelsbach in October 1200, the Cathedral chapter of Mainz and King Philip of Swabia recognised Leopold II of Schönfeld as the new archbishop. However a minority of the chapter of the Welf party instead chose Siegfried as the archbishop. Leopold drove Siegfried out of the archbishopric but he fled to Cologne where the Welfists there helped him conquer Bingen and Mainz. On Christmas Day in 1200 he crowned Otto of Brunswick the anti-King of Germany. In 1201 Pope Innocent III recognised Siegfried as the legal archbishop of Mainz and Otto the legal king of Germany.

However Philip of Swabia attracted many supporters and as the Pope took a pro-Hohenstauffen position in 1205 Siegfried lost all chance of ruling in Mainz. In 1206 he went to Rome and was active in Sabina. In June 1208 Philip of Swabia was murdered, and losing his vital support Leopold of Schönfeld fled Mainz to Worms. Siegfried returned to Mainz that year as a papal legate. In 1209 Otto of Brunswick and the Pope again entered into a new dispute as the former demanded his rights in Italy, and Siegfried placed himself against his former ally Otto. In 1212 he helped elect the Hohenstauffen Frederick II as Emperor and crowned him. Otto punished Siegfried'z betrayal by laying waste the lands around Mainz.

In 1214 Otto and King John of England were defeated by the army of King Philip II of France at the Battle of Bouvines and fled to his ancestral lands of Brunswick. Siegfried recrowned Frederick II in Aachen in 1215. In 1220 he also participated in Frederick's coronation by the Pope in Rome. Siegfried did not take part in the controversy between Frederick II and Pope Gregory IX. He died in Erfurt in 1230 leaving the archbishopric in heavy debt, and was buried in Mainz Cathedral. He was succeeded by his nephew Siegfried III of Eppstein.

Preceded by:

Siegfried II of Eppstein

Succeeded by:

Leopold II of Schönfeld Archbishop of Mainz
1200 - 1230
opposed Leopold II of Schönfeld
1200 - 1208
Siegfried III of Eppstein