After studying at Oxford, and at Gray's Inn, Dudley came under the notice of Henry VII, and is said to have been made a Privy Councillor at the early age of 23.

[3] He and his colleague Sir Richard Empson were prominent councillors of the Council Learned in the Law, a special tribunal of Henry VII's reign, which collected debts owed to the king, requested bonds as surety, and employed further financial instruments against high-born and wealthy subjects.

While collecting the king's money, Dudley amassed a great amount of wealth for himself, which resulted in estates in Sussex, Dorset, and Lincolnshire.

Dudley's nominal crime was that during the last illness of Henry VII he had ordered his friends to assemble in arms in case the king died, but the real reason for his charge was his unpopularity stemming from his financial transactions.

During his imprisonment, Dudley sought to gain the favour of King Henry VIII by writing a treatise in support of absolute monarchy, called The Tree of Commonwealth.