Wenceslas was born to the royal Premysl dynasty of Bohemia (current part of the Czech Republic). The dynasty united the warring tribes of Bohemia into one duchy. The first known Premysl ruler was Wenceslas's grandfather, Duke Borivoy I, who made Prague Castle the family seat. He married a Slav princess named Ludmila, and both eventually became Christians. When Borivoy died he was succeeded by his sons, Ratislav and Spythinev. Ratislav was Wenceslas's father.

Wenceslas was born around 907 in the castle of Stochov near Prague. At first Wenceslas was raised by his grandmother, Ludmila. Then, when he was about 13 years old, his father died. Wenceslas succeeded him as duke. But because he was too young to rule, his mother, Drahomira, became regent. Drahomira was opposed to Christianity and used her new power to persecute followers of the religion. She refused to let Wenceslas see Ludmila because she was afraid they would scheme to overthrow her. Not long after Ratislav's death, Ludmila was murdered at Tetin Castle - strangled, it is said, at Drahomira's command. After her death Ludmila was revered as a saint.

But the loss of his grandmother did not stop Wenceslas from seizing power. At the age of 18 he overthrew his mother's regency, just as she had feared, and began to rule for himself. A stern but fair monarch, he stopped the persecution of priests and tamed the rebellious nobility. He was known for his kindness to the poor. Many of the Bohemian nobles resented Wenceslas's attempts to spread Christianity, and were displeased when he swore allegiance to the king of Germany, Henry I.

The duke's most deadly enemy proved to be his own brother, Boleslav, who joined the nobles who were plotting his brother's assassination. He invited Wenceslas in 935 AD to a religious festival and then attacked him on his way to mass. As the two were struggling, Boleslav's supporters jumped in and murdered Wenceslas. Wenceslas became Bohemia's most famous martyr and patron saint.