The Act of Uniformity 1558 was an Act of the Parliament of England, passed in 1559,^{[lower-alpha 3]} to regularise prayer, divine worship and the administration of the sacraments in the Church of England. In so doing, it mandated worship according to the attached 1559 Book of Common Prayer. The Act was part of the Elizabethan Religious Settlement in England instituted by Elizabeth I, who wanted to unify the church. Other Acts concerned with this settlement were the Act of Supremacy 1558 and the Thirty-Nine Articles.

Elizabeth was trying to achieve a settlement after 30 years of turmoil during the reigns of Henry VIII, Edward VI and Mary I, during which England had swung from Roman Catholicism to Protestantism and back to Catholicism. The outcome of the Elizabethan Settlement was a sometimes tense and often fragile union of High Church and Low Church elements within the Church of England and Anglicanism worldwide.

The Act set the order of prayer to be used in the 1559 Book of Common Prayer. All persons had to attend Anglican services once a week or be fined 12 pence (equal to about three days wages).^{[lower-alpha 4]}

On 27 September 1650, the Act was repealed by the Rump Parliament of the Commonwealth of England with the "Act for the Repeal of several Clauses in Statutes imposing Penalties for not coming to Church",^[3] but this Act was rendered null and void with the Restoration of the monarchy in 1660. Most of the Act was repealed by the Statute Law Revision Act 1888.

• Acts of Supremacy
• Acts of Uniformity
• Conformist
• Nonconformist
• Religion in the United Kingdom
• A View of Popish Abuses yet remaining in the English Church