Seventh Tree received rave reviews and became the duo's most critically acclaimed album since their 2000 debut Felt Mountain, with critics praising their new sound and their bravery for abandoning the dance atmosphere of their previous two albums. The album debuted at number two on the UK Albums Chart with 46,945 copies sold in its first week.
Four singles were released from the album. "A&E" was released as the lead single on 11 February 2008, peaking at number 10 on the UK Singles Chart. The album's second single, "Happiness", peaked at number 25 on the UK chart, while the third single, "Caravan Girl", reached number 54. "Clowns" was released as the fourth and final single, charting at number 115 in the UK.
Seventh Tree received generally positive reviews from music critics. At Metacritic, which assigns a weighted mean rating out of 100 to reviews from mainstream critics, the album received an average score of 78, based on 32 reviews, which indicates "generally favorable reviews".Barney Hoskyns of The Observer commented that the duo "have made an album as hummably lovely as it is knowingly referencing of a certain tradition of neo-psychedelic English whimsy." Genevieve Koski of The A.V. Club noted that the album is "buoyed by an underlying pop sensibility, epitomized by the bubbly 'A&E;' and 'Caravan Girl'", concluding, "After the group's hit-or-miss synth-pop detour, Seventh Tree situates Goldfrapp where it was always meant to be." John Murphy of musicOMH viewed it as Goldfrapp's "most subtle, affecting and rewarding album to date" and compared it to Kate Bush and the Cocteau Twins. At AllMusic, Heather Phares praised the album's "electro hippie-chic" as the duo's "most polished and luxe work yet". John Lewis of Uncut called it "brave, bonkers, often beautiful, sometimes haunting and occasionally ridiculous".
PopMatters' Adrien Begrand found that Seventh Tree "might be a quieter and more introspective disc than we'd been expecting, but this is still a quintessential Goldfrapp album with Gregory's arrangements brilliantly underscoring the inimitable vocal versatility of his female foil." Despite being critical of Alison Goldfrapp's "wispy, ethereal, often impenetrable vocal approach", Dave Hughes of Slant Magazine opined that the album is "most compelling for the way in which the band's regained austerity and naturalism contrasts with their more recent hedonism." Kat Lister of the NME expressed that "Seventh Tree is bound to ruffle a few electro-feathered fans, but there's no denying it's a venture that sets the pair into new experimental territory." In a mixed review, Rolling Stone's Christian Hoard felt that the "slow pace can be a snooze", but wrote that the album "still makes for good post-party chill-out music". Nate Patrin of Pitchfork Media was less impressed, stating that the album's ambience is "so subtle and slow-moving it doesn't seem to go anywhere, and it coasts on some frothy sense of pleasantness that evaporates the moment the song ends."
Q magazine ranked the album at number 19 on its list of The 50 Best Albums of 2008.PopMatters placed it at number 54 on its list of The Best Albums of 2008.Ben Rayner of the Toronto Star included the album on his list of "rock music that stuck in 2008".
Seventh Tree debuted at number two on the UK Albums Chart, selling 46,945 copies in its first week. It was certified gold by the British Phonographic Industry (BPI) within four days of release, on 29 February 2008. As of March 2010, the album had sold 200,062 copies in the United Kingdom. The album reached the top 10 in Belgium and Ireland, and the top 20 in Australia, Norway, Portugal and Switzerland.
Seventh Tree became Goldfrapp's second release to chart on the Billboard 200 in the United States, where it debuted at number 48 with first-week sales of 15,000 copies. The album also peaked at number 28 on the Canadian Albums Chart.
A special edition of Seventh Tree was released on 3 November 2008, featuring new album artwork, photographs and a DVD. The album artwork depicted Goldfrapp dressed as a clown and hugging a tree, as well as Gregory dressed as an owl. The DVD contained music videos, behind-the-scenes footage and several live performances filmed at the De La Warr Pavilion in Bexhill-on-Sea in June 2008.