It borders four other London boroughs – Barnet to the east of ancient Watling Street (now the A5 road), Brent to the southeast, Ealing to the south and Hillingdon to the west and the Hertfordshire districts of Three Rivers and Hertsmere to the north.

The borough is made up of three towns: Harrow, Pinner and Stanmore, but also includes western parts of Edgware.

The local board district covered the original hilltop village and the adjoining hamlets of Roxeth, Sudbury and Greenhill.

[5] Greenhill subsequently developed into the modern town centre of Harrow following the opening of Harrow-on-the-Hill station there in 1880.

[14][15] Since 2000, for elections to the London Assembly, the borough forms part of the Brent and Harrow constituency.

This has a programme of dance, world music, sports activity, youth music, spoken word, free children's activity, a carnival parade, information and stalls, health promotion, a world food zone and outside radio broadcast.

[34] Grade I and II* buildings in the borough include the Church of St Lawrence, Stanmore and Headstone Manor, and Grade II listed buildings include Bentley Priory, Grim's Dyke and Harrow and Wealdstone station.

Major employers included Kodak,[35] the Royal National Orthopaedic Hospital and Ladbrokes, which formally has its headquarters in Harrow.

Hatch End Cricket Club previously played at Shaftesbury playing fields in Hatch End but following an arson attack on their clubhouse and a subsequent failure to raise enough funds to build a new one, the club moved to Elstree in 2011.

Harrow also had a professional rugby league team when London Broncos played at The Hive Stadium in 2014 and 2015.

The borough is often perceived as having a good educational record, and features many state-funded primary and secondary schools as well as a handful of large tertiary colleges.

From September 2010, the primary sector was modified to enable transfer to secondary education at age 11 in line with other London Boroughs.

Meanwhile, the Piccadilly and Metropolitan lines pass through the southern edge of the borough on shared track before both terminating at Uxbridge.

The Northern line terminates just outside Harrow at Edgware tube station in the London Borough of Barnet.

The London Overground also serves the borough, sharing track with the Bakerloo line between Queens Park and Harrow & Wealdstone before it continues beyond the latter station to eventually terminate at Watford Junction.

The numerous National Rail, London Overground and London Underground stations in the borough are: In March 2011, the main forms of transport that residents used to travel to work were: driving a car or van, 27.5% of all residents aged 16–74; underground, metro, light rail, tram, 5.9%; bus, minibus or coach, 5.9%; train, 4.5%; on foot, 4.3%; work mainly at or from home, 3.5%; passenger in a car or van, 1.6%.

The motto reads as "Salus Populi Suprema Lex" which translates from Latin as "The well-being of the people is the highest law.