21, Onslow Square has an Energy Performance Rating (EPC) of C. This is based on the most recent assessment, dated 17 Apr 2025.

The property is connected to mains gas and has partial secondary glazing. It is heated using a boiler and radiators (mains gas).

According to the Land Registry and our network of Estate Agents, there have been 16 sales of properties similar to 21, Onslow Square within a radius of 280 metres since 2011.

The most recent example is Flat 2, 11, Onslow Square, London, SW7 3NJ, a leasehold flat which sold for £2,750,000 on the 20th November 2025.

Read more about house prices in SW7.

• Sold Nov 2025£2,750,000 | 3 Bed FlatFlat 2, 11, Onslow Square, London, SW7 3NJFlat 2, 11, Onslow Square, London, SW7 3NJ
• Sold Nov 2024£2,825,000 | 3 Bed FlatFlat 2, 23, Onslow Square, London, SW7 3NJFlat 2, 23, Onslow Square, London, SW7 3NJ
• Sold Oct 2022£3,100,000 | 3 Bed Flat42, Rose Square, London, SW3 6RS42, Rose Square, London, SW3 6RS
• Sold Aug 2022£3,600,000 | 3 Bed FlatFlat 1, 17, Onslow Square, London, SW7 3NJFlat 1, 17, Onslow Square, London, SW7 3NJ
• Sold Mar 2021£2,300,000 | 3 Bed Flat1, Onslow Square, London, SW7 3NJ1, Onslow Square, London, SW7 3NJ
• Sold Oct 2018£2,650,000 | 3 Bed FlatFlat 2, 52, Onslow Square, London, SW7 3NXFlat 2, 52, Onslow Square, London, SW7 3NX
• Sold Jun 2018£3,000,000 | 3 Bed FlatFlat 1, 38, Onslow Square, London, SW7 3NSFlat 1, 38, Onslow Square, London, SW7 3NS
• Sold Jun 2016£4,140,000 | 3 Bed FlatFlat 2, 44, Onslow Square, London, SW7 3NXFlat 2, 44, Onslow Square, London, SW7 3NX
• Sold Mar 2016£4,400,000 | 3 Bed Flat19, Onslow Square, London, SW7 3NJ19, Onslow Square, London, SW7 3NJ
• Sold Mar 2015£3,250,000 | 3 Bed FlatFlat 5, 52, Onslow Square, London, SW7 3NXFlat 5, 52, Onslow Square, London, SW7 3NX
• Sold Feb 2015£3,100,000 | 3 Bed FlatFlat 4, 52, Onslow Square, London, SW7 3NXFlat 4, 52, Onslow Square, London, SW7 3NX
• Sold Dec 2014£3,950,000 | 3 Bed FlatFlat 6, 81, Onslow Square, London, SW7 3LTFlat 6, 81, Onslow Square, London, SW7 3LT
• Sold Nov 2014£3,250,000 | 3 Bed FlatFlat 5, 38, Onslow Square, London, SW7 3NSFlat 5, 38, Onslow Square, London, SW7 3NS
• Sold May 2014£3,900,000 | 3 Bed FlatFlat 3, 38, Onslow Square, London, SW7 3NSFlat 3, 38, Onslow Square, London, SW7 3NS
• Sold Feb 2013£2,300,000 | 3 Bed FlatFlat 5, 5, Onslow Square, London, SW7 3NJFlat 5, 5, Onslow Square, London, SW7 3NJ
• Sold Jan 2011£2,250,000 | 3 Bed FlatFlat 3, 89, Onslow Square, London, SW7 3LTFlat 3, 89, Onslow Square, London, SW7 3LT

Onslow Square, London, SW7 has a total of 321 addresses. According to our analysis of all the public data, 21, Onslow Square is the 138th largest and the 69th most expensive property on the street.

When compared to the postcode district it is £700k more expensive than the average property in SW7.

• Oratory Roman Catholic Primary School

  300 m away
• Marlborough Primary School

  400 m away
• Our Lady of Victories RC Primary School

  500 m away

• St. Thomas More Language College

  700 m away
• Chelsea Academy

  1.8 km away
• The London Oratory School

  1.9 km away

• South Kensington

  |

  200 m away
• Gloucester Road

  |

  700 m away
• Knightsbridge

  |

  1.0 km away

According to data from the Environment Agency, the flood risk in this area is considered to be Very Low.