People across the UK were asked to rate their happiness by the Office for National Statistics (ONS), which published its latest findings on Tuesday (February 2).
The average score in Kensington & Chelsea was 7.56 out of 10, compared with 7.17 for Hammersmith & Fulham.
Ealing (7.45), Hounslow (7.40) and Harrow (7.39) were all above the average London rating of 7.31 and the UK-wide score of 7.38.
Denizens of Brent (7.31) were no cheerier than the average Londoner, while residents of Hillingdon (7.25) and Westminster (7.21) were less content.
Just over 300,000 people across the UK were quizzed about their state of mind by the ONS for the survey between April 2012 and March 2015.
As well as being asked how happy they felt, participants were invited to grade their levels of anxiety, life satisfaction and how worthwhile they felt their lives were.
The findings so far suggest people aged 65-79 are generally happiest with their lot in life, while levels of discontent are highest among those aged 45-59.
The ONS' latest statistics on wellbeing contrast with the previous figures from the survey , which were published in September 2015.
Hounslow was top of the pile in west London back then, with a happiness rating of 7.56, while those in Hillingdon (7.31) were the glummest on this side of the capital at the time.
A survey by the property website Rightmove , the results of which were published last August, found Hounslow was the second most miserable place to live in the UK.
Eilean Siar, in Scotland, is now the UK's cheeriest place, according to the ONS survey, with a happiness rating of 8.08.
Liverpool is the country's glummest region, with a score of just 6.96.
How happy is your borough?
|Borough||Happiness rating (average score out of 10)|
|Kensington & Chelsea||7.56|
|Hammersmith & Fulham||7.17|
* all figures from ONS Annual Population Survey of Personal Wellbeing