Thank You has received generally positive reviews. At the online music guide Allmusic, the album received a rating of four stars out of five. It also received a generally positive review from the BBC. Commercially, Thank You remains Jamelia's most successful album to date. In the United Kingdom, Thank You reached a new peak of #4 following its re-release in March 2004, thus becoming Jamelia's highest charting album to date. It has since been certified 2× Platinum by the British Phonographic Industry (BPI) for sales in excess of 600,000 copies. Elsewhere in the world, Thank You has reached the top twenty in New Zealand and the top forty in Ireland and Switzerland.
The album produced seven singles, all of which attained varying degrees of international chart success. "Bout" was released as the album's lead single In June 2003. It featured guest vocals from Rah Digga and reached the top forty in the United Kingdom. The follow-up single, "Superstar" became Jamelia's most successful single internationally to date, topping the charts in Australia and New Zealand. The title track was released as the album's third single in February 2004 and became Jamelia's highest charting single in the UK to date, peaking at #2 on the UK Singles Chart. Following the single's success, the album was re-released with two additional tracks (three including Jamelia's duet with Italian singer Tiziano Ferro on the single, "Universal Prayer", which was only included on international versions of the re-release). "See It In a Boy's Eyes" served as the first single from the re-release and as the album's fourth single overall. It was most successful in the United Kingdom, where it became Jamelia's third consecutive top five hit. "Universal Prayer", a duet with Italian singer Tiziano Ferro, served as the album's fifth single and became Jamelia's first number-one hit in Italy and Spain. The album's final two singles, "DJ" and "Stop!" were released jointly as a double a-side single and became Jamelia's fourth consecutive top ten hit in the United Kingdom.