It is bordered by the counties of Carlow, Laois, Meath, Offaly, South Dublin and Wicklow.

The Grand Canal crosses the county from Lyons on the east to Rathangan and Monasterevin on the west.

Kildare was shired in 1297[5] and assumed its present borders in 1832, following amendments to remove a number of enclaves and exclaves.

Kildare County Council nominates three councillors to the Eastern and Midland Regional Assembly, who are part of the Mid-East strategic planning area committee.

[13] At the 2020 Irish general election, Kildare North returned Catherine Murphy (SD), Réada Cronin (SF), Bernard Durkan (FG), and James Lawless (FF), while Kildare South returned Sean Ó Fearghaíl (FF) (returned automatically as outgoing Ceann Comhairle), Patricia Ryan (SF), Martin Heydon (FG), and Cathal Berry (Ind).

The northeastern region of Kildare had the highest average per-capita income in Ireland outside County Dublin in 2003.

The N4 (M4) from Dublin to Sligo travels along the north of the county by-passing the towns of Leixlip, Maynooth and Kilcock.

The M7 from Dublin to Limerick runs through the county and bypasses the towns of Naas, Newbridge, Kildare and Monasterevin.

The principal Irish Rail InterCity train station in the county is Kildare, however, Newbridge, Sallins and Hazelhatch are also served by South Western Commuter services, while Maynooth, in northern County Kildare, is served by Western Commuter and Sligo InterCity services.

Kildare is the centre of Ireland's Grand Canal network built in the late 18th century.

The Royal Canal runs west from Dublin and parts of it form the boundary with County Meath.

In 1928, Kildare became the first team to win the Sam Maguire trophy for the All-Ireland Senior Football Championship, defeating Cavan 2–6 to 2–5.

However, since then Kildare has reached the All-Ireland Football Championship Final on four occasions, the last being in 1998, but has failed on all four attempts.

The Michael Smurfit owned K Club, situated on the River Liffey near Straffan played host to the 2006 Ryder Cup.

Also located in County Kildare are two other courses, Punchestown Racecourse, home of the National Hunt Festival of Ireland, and Naas Racecourse, which runs both National Hunt and Flat meetings and is used by top racehorse trainers as a test for horses preparing for the Cheltenham festival.

was invited to join the league in 2002, however, a broader Kildare-based franchise was created instead, playing out of Station Road, Newbridge.

County Kildare is twinned with the following places: Both are major centres of the Thoroughbred breeding industry in their respective countries.