Browne, Geoffrey (d. 1668), lawyer and politician, was the eldest son, of the four sons and five daughters, of Sir Dominick Browne, merchant, and mayor of Galway in 1634, and his wife, Anastasia, daughter of James Darcy, mayor of Galway in 1603, and sister of Patrick Darcy (qv). Browne was admitted to the Middle Temple, London, on 30 June 1627, and to King's Inns in 1637. An active barrister, he was a legal advisor to Galway corporation and to Richard Burke (qv), earl of Clanricard. He married Mary Lynch, daughter of Sir Henry Lynch of Galway; they had five sons and one daughter. On 27 February 1640 he was elected an MP for Athenry, Co. Galway, and played a prominent role in parliament in 1640–41, serving on several commons committees including that sent to England in late 1640.
Following the outbreak of the 1641 rising, Browne appears to have returned to Galway, being involved in that town's negotiations with Ulick Burke, marquess of Clanricarde (qv), in May 1642. He was elected to the first confederate supreme council on 11 November 1642, and was a member of consecutive supreme councils until February 1646. He was also one of the principal figures in the negotiations between confederate representatives and the Dublin administration of James Butler, marquess of Ormond (qv), serving on all of the negotiating committees appointed by the confederate general assemblies between May 1643 and 1648–9, and as such was a signatory of the cessation of 15 September 1643 and one of the confederate agents sent to Oxford to deal directly with Charles I in 1644. He has come to be regarded as a leading figure among the confederate peace party, prioritising a peace with Charles I in light of the possible threat to the confederates from a parliamentarian victory in England, and eager to circumvent contentious religious negotiations in the interests of a settlement. He signed the first Ormond peace of March 1646; when this was repudiated by the confederate faction led by Archbishop GianBattista Rinuccini (qv), he was arrested in Galway.
In November 1647 the confederate general assembly named Browne one of their agents to the exiled court of Queen Henrietta Maria in France. He was one of the small committee who selected the new supreme council of December 1647, and was named a supernumerary member. Arriving in Paris in mid-March 1648, he again cooperated with Ormond, now in exile, again seeking an arrangement that put religious concessions on hold, and allowed Ormond to return to Ireland as the crown's negotiator. He was involved in negotiations for, and was a signatory of, the second Ormond peace of 17 January 1649; he was one of the commissioners of trust who took office under that treaty in place of the last confederate supreme council.
On 25 June 1650 he was among those named by Ormond to negotiate with an agent from Charles, duke of Lorraine, who had offered aid against the forces of the English parliament. The following year Ormond's deputy, Clanricarde, named Browne as one of three agents to travel to the Netherlands to treat further with Lorraine. He reached Brussels on 12 June 1651 and signed an agreement with Lorraine on 22 July. The concession of the rank of royal protector of Ireland, however, led to Clanricarde's rejection of the treaty and accusation that Browne and his associates had betrayed their trust; the treaty duly collapsed. By September 1651 he was suggesting to Clanricarde the possible necessity of making terms with the English parliamentarians following the collapse of Charles II's military fortunes in England.
Browne returned to Ireland in October 1651 but his activities for the next few years are unclear. On 12 August 1652 he was named among those excepted from pardon for life and estate by the parliamentarians, and appears to have been in London in May 1653. On 30 April 1661 he was returned as an MP for Tuam, Co. Galway, the only catholic elected to that parliament, but was unseated by the commons.
Browne was heir to his father's extensive lands in counties Galway and Mayo. Partially confiscated from Sir Dominick Browne in 1653, these were ordered restored to Geoffrey Browne by Charles II on 13 February and 27 June 1661. He was included in the terms of the 1662 Act of Settlement, but he died before the award of patents for the properties, duly conferred on his son Dominick in 1670 and 1678. His descendants obtained the title of lords Oranmore and Browne. He died 14 January 1668.