Since its release at the end of February her Island/Lava debut Who You Are had sold around 530,000 copies in the UK by last Sunday, according to the Official Charts Company. This total dwarfs the collective album sales of the 11 other acts on the 15-strong list who have already had an album out.
The nearest act to Jessie J's total are Columbia signings The Vaccines - third on the BBC poll, which is selected by music critics and tastemakers - whose introductory album What Did You Expect From The Vaccines? has sold around 150,000 copies domestically.
It is the only other album by an act on the widely-publicised long list to have already reached six figures, but has been outsold by nearly three-and-a-half copies to one by Who You Are.
The acts who respectively finished in second, fourth and fifth places on the BBC Sound Of... rankings, announced in December last year, are even further behind in album sales.
Runner-up James Blake's self-titled Atlas/A&M album has to date shifted in the region of 50,000 copies while fourth-placed Jamie Woon's introductory Mirrorwriting has sold 20,000 units. Fellow Polydor act Clare Maguire has followed fifth position on the list with around 55,000 UK sales of album Light After Dark.
The most successful of the other 10 acts that made up the initial long list have been MTA/ Mercury's Nero who topped the UK singles chart last month with Promises and then debuted at number one the following week with their first album Welcome Reality. In three weeks it has sold 55,000 copies in the UK, while Ministry of Sound act and fellow BBC Sound Of... contender Wretch 32's album Black And White has sold about 40,000 copies since its release a fortnight ago.
Five of the other artists on the long list who already have albums out have had far longer to build up album sales than Nero and Wretch 32, although none by last week had got above the 40,000 mark.
Rough Trade act Warpaint are the nearest with their album The Fool, released last October, having sold around 38,000 units. They got a mini sales boost after their Glastonbury appearance was broadcast by BBC Television in June.
Domino artist Anna Calvi's self-titled album is around the 25,000 mark following its release in January. It is likely to get a boost this week as it was shortlisted for the Barclaycard Mercury Prize, as was James Blake's album, while album sales of three Universal acts longlisted remain below 25,000 units.
New Zealand alternative band The Naked And Famous's Passive Me, Aggressive You has sold about 24,000 copies since its mid-March release by Fiction, while Fat Possum/Mercury act Yuck's self-titled debut, which was released in February, has so far had about 16,000 takers domestically. Meanwhile, Nashville rock band Mona, who were subject to one of the big A&R scrambles of 2010 before settling with Island, have seen their own eponymous debut shift little more than 10,000 copies since its May 16 release.
Three acts on the long list have not had an album out: Daley, Esben and the Witch and Jai Paul, although XL issued a single by Paul (BTSTU) in April.
Leading 2011's list, Jessie J - who was also the Critics' Choice winner at this year's Brit Awards - has also comfortably sold more albums at this stage in the year than the respective champs of the BBC Sound Of... in the previous four years.
The 2008 winner Adele's first album 19 had shifted 390,000 copies by the autumn of that year, although her album has now sold 1.7 million copies in the UK, including around 970,000 this year.
Little Boots' 679-issued debut Hands had sold in the region of 63,000 copies by the start of September 2009 after winning that year' poll.
The debuts by the other four shortlisted acts in 2009 all outsold it, while more than 200,000 copies had been snapped up by the beginning of September last year of Ellie Goulding's album Lights after she claimed the 2010 prize.
Who You Are's sales to date stack up very impressively compared to how many albums the other acts shortlisted in the BBC Sound Of... poll during the previous five years had sold up to the same point on the calendar. Only three acts did better. They are 2007 winner Mika, whose Casablanca/Island debut Life In Cartoon Motion shifted around 700,000 copies by the start of September that year, 2008 champ Duffy and Lady GaGa, who followed sixth place on the 2009 poll with 700,000 sales of her first album The Fame in the first nine months of that year.
However, Jessie J's success flies in the face of what has been a definite decline in how many albums acts now sell after being shortlisted.
As is the case this year, only two of the top five artists on the 2010 survey - Ellie Goulding and Atlantic's Marina & The Diamonds - had sold more than 100,000 albums by September last year, compared to 2008 when four of the five managed it - Fiction's White Lies, Island's Florence + The Machine, Virgin's Empire Of The Sun and Polydor's La Roux, plus sixth-placed Lady GaGa.
A year earlier debuts by the poll's top three of Adele, Duffy and Columbia's The Ting Tings surpassed 100,000 sales by the start of September 2008, while fourth-placed Glasvegas quickly followed suit with their own Columbia debut, which was not released until September 8 that year.
The decline in fortunes each year for the shortlisted acts clearly reflects a general fall overall in annual album sales and what continues to be a greater difficulty in breaking new acts.
But the trend may also indicate the declining influence of such annual tastemaker surveys on music fans' buying. Where once being at the top end of this list would almost guarantee a big breakthrough would follow, now it is just the first step on what could be a very tricky path to success.