The band entered Roger Taylor's Priory studio in late 2006 having completed the American leg of their world tour. Sessions were initially scheduled around Rodgers' other touring commitments. On the previous tour the band had debuted a new song, "Take Love", which did not make the album. Throughout the promotion for his solo tour, Rodgers' also debuted songs such as "Warboys", and "Voodoo". John Deacon's continued retirement meant that bass duties are shared between Rodgers and May. The first single, "Say It's Not True" was released nine months before the album was released. The second single, "C-lebrity" was previewed on Al Murray's Happy Hour in April, five months before the album was released. The album's release came 17 years after the death of Queen's lead singer, Freddie Mercury, in 1991.
"Say It's Not True" was the lead single from the album, released in the UK on 31 December 2007; it reached #90 in the British charts although had been available as free download for some time. Its video features many clips of the suffering in South Africa as well as clips from Nelson Mandela's 46664 concerts. The single was released for the 46664 charity, with all proceeds being donated there.
"C-lebrity" was released as the album's second single on 8 September 2008, reaching #33 in the UK singles charts. Its B-side was a recording of "Fire and Water" live in Japan.
"We Believe" was released as a promo single in Italy, and reached #4 in the Virgin radio charts. It was edited down from its original 6-minute album version to less than 4 minutes.
Cosmos Rocks received mixed-to-negative reviews. According to critic review aggregator Metacritic, the album received an average review score of 42/100, which ranks it at 28th place on Metacritic's "worst-reviewed"' albums list. A review on website Pop and Rock gave it two out of five stars "the lyrics were stupid, trite, a bit offensive and bound to have an undermining effect on whatever musical efforts they put behind it". On the other hand, PopMatters gave it a 7/10 review, stating, "Paul Rodgers breathes new life into Queen, while still keeping the band's tremendous legacy intact as they soldier forth with new material into the 21st century". Mojo gave it three stars, stating, "Occasionally they stumble, as on the clunky 'Warboys.' But with Rodgers imperious, Queen's second coming is vindicated".
The "Rock the Cosmos Tour" began in September 2008 to promote the release of this album. The opening date was recorded for a DVD release, and was broadcast across digital video theatres across the United States on 6 November 2008 under the title "Let the Cosmos Rock". The tour included one of the largest open-air concerts in Kharkiv, Ukraine, which garnered 350,000 people. Over the course of the tour, Queen played to just short of a million viewers.
^"Czech Albums – Top 100". ČNS IFPI. Note: On the chart page, select 200839 on the field besides the word "Zobrazit", and then click over the word to retrieve the correct chart data. Retrieved 23 January 2013.