Otto was born in Swabia, present-day Bavaria which is in southern Germany and came from a rich family. He became a priest and entered the service of Emperor Henry IV. About then years later, Father Otto became Henry's chancellor.
Otto tried to convince the emperor to act fairly and to be reasonable when faced with decisions. But Henry did many wrong things, causing trouble and tried to split the Church into two groups. He even appointed his own pope. Otto felt very bad and did his best to help Henry change.
Henry IV then appointed Otto as bishop but Otto refused saying that only the true pope in Rome, Pope Paschal II had the power to do this. Henry was forced to agree and Otto traveled to Rome where he was consecrated a Bishop.
Bishop Otto became a great help to the people of Swabia, especially under Emperor Henry V. This emperor followed his father, Henry IV's bad habits. But although he was unkind and very strict, he respected Otto and often listened to his advice.
When King Boleslaus III of Poland conquered part of Pomerania in Prussia, he asked Otto to go there. The people there were pagans and believed in false gods. Bishop Otto welcomed the chance to tell them about Jesus and God's great love for people. A couple of years later, the bishop led a group of priests and catechists into Pomerania.
More people were taught the faith and more than twenty thousand people were baptized. Bishop Otto appointed priests to minister to the new Christians. He returned to his own country and then a few years later the people of Pomerania began to return to their old pagan ways.
When he heard this, Bishop Otto went back to Pomerania helping the people become fervent Christians again. He started more than twenty monastries, built churches and worked hard to heal the problems between the king and the pope. He died on June 30, 1139.