The Castle Hill convict rebellion was a convict rebellion in Castle Hill, Sydney, then part of the British colony of New South Wales. Led by veterans of the Irish Rebellion of 1798, the poorly armed insurgents confronted the colonial forces of Australia on 5 March 1804 at Rouse Hill. Their rout in the resulting skirmish was hailed by loyalists as "Australia's Vinegar Hill" after the 1798 battle of Vinegar Hill, where Society of United Irishmen rebels were decisively defeated. The incident was the first major convict uprising in Australian history to be suppressed under martial law.

On 4 March 1804, 233 convicts, led by Philip Cunningham, a veteran of the Irish Rebellion of 1798 as well as a mutineer on the convict transport Anne, escaped from a prison farm, intent on "capturing ships to sail to Ireland". In response, martial law was quickly declared in the colony. The mostly Irish rebels, having gathered reinforcements, were pursued by colonial forces under George Johnston until they were caught on Rouse Hill on 5 March 1804.

While negotiating under a flag of truce, Cunningham was arrested. Johnston's troops then charged and scattered the rebels, and the rebellion was suppressed. Nine of the rebel leaders were executed, and hundreds were punished, before martial law was revoked a week after the battle.

Many convicts in the Castle Hill area were veterans of the United Irish movement and of the rebellion it had instigated in Ireland in the summer of 1798. From late 1799, they were transported as exiles-trial to the Colony of New South Wales. In September 1800, an Irish conspiracy was uncovered. The rebels planned to meet at and take Parramatta, and then before daylight take the Barracks at Sydney. Afterwards they planned to live on settlers farms, until they heard from France, where they had intended to dispatch a ship.

Early in 1804, after news arrived of Robert Emmet's attempted rising in Dublin the previous July, a similar conspiracy formed. Phillip Cunningham, a veteran of the rebellion of 1798, and William Johnston, another Irish convict at Castle Hill, planned an uprising. Over 685 Castle Hill convicts intended to join with nearly 1,100 convicts from the Hawkesbury River area, rally at Constitution Hill, and march on Parramatta and then Sydney Port Jackson itself. According to Helen Mackay, their goal was to establish Irish rule in the colony and obtain ships for those that wanted to return to Ireland to help revive the failed Irish Rebellion of 1803.

At 8 o'clock on the evening of 4 March 1804, John Cavenah set fire to his hut at Castle Hill as the signal for the rebellion to begin. While the fire was not seen by the convicts at Green Hills, today's Windsor, on the Hawkesbury River, Cunningham activated the plan to gather weapons, ammunition, food and recruits from local supporters and the government farm at Castle Hill. With Cunningham leading, about 200 to 300 rebels broke into the Government Farm's buildings, taking firearms, ammunition, and other weapons.

The constables and overseers were overpowered and the rebels then went from farm to farm on their way to Constitution Hill at Parramatta, seizing more weapons and supplies, including rum and spirits, and recruiting others to fight their cause. Their move had been informed by the intelligence gathered a year previously, when 12 convicts escaped from Castle Hill, seeking out friends and sympathisers in the surrounding districts. When captured, every convict had the same story: they were heading to China by crossing over the Blue Mountains.

When news of the uprising spread there was great panic amongst the colony of around 5,000 inhabitants. Officials such as Samuel Marsden fled the area by boat, escorting Elizabeth Macarthur and her children, because an informer had advised that an attack would be made on the Macarthur's farm so as to draw troops away from Parramatta. On receipt of the news of the uprising, Governor King set off alone for Parramatta to assume command, while Colonel William Paterson, the lieutenant governor, called out the guard.