Rio received mainly positive reviews on release. At Metacritic, which assigns a normalised rating out of 100 to reviews from mainstream critics, the album has received a score of 90, based on 8 reviews which is categorised as universal acclaim. The Allmusic review by Thom Jurek awarded the album 4½ stars, stating, "After one listen, it becomes obvious Rio is indeed very special. It puts on aural display Jarrett as a virtually boundless musician, whose on-the-spot, wide-ranging ideas are executed with astonishing immediacy and dexterity; this music is passionate, poetic, and stands outside the confines of genre... since nothing approaching what is here actually exists in Jarrett's recorded catalog. Rio is therefore the new standard by which the pianist's future solo recordings will be judged, and perhaps also sets the bar for any other player who attempts the same". The Guardian's John Fordham said, "Rio represents Jarrett at his most exuberant'. On PopMatters, Will Layman noted, "Rio is the most brilliant Jarrett solo recording in recent memory. Rather than improvising in a longer, more rambling form, Jarrett works here in shorter statements, each focused and concise. In 15 very different miniatures, Rio demonstrates the pianist's astonishing facility for generating not only grooves or settings but also developing webs of melody and counter-melody. From free playing to blues to gospel to aching ballads, Jarrett covers a vast landscape of piano.". The Independent's Andy Gill said, "these 15 pieces sketch an entire world of music, coloured by the locale, and shifting between the smoothly lyrical and the propulsively rhythmic, with Jarrett's familiar, pulsing left-hand figures providing a stolid foundation anchoring the serpentine runs of his right hand". The Independent on Sunday's Phil Johnson compared it to Jarrett's most successful release, stating, "The second of the two discs is a lyrical triumph to equal the Koln Concert, intense drama and emotional catharsis captured through long-haul, improvised performance". The Daily Telegraph's Ivan Hewett was less enthusiastic, observing, "There are good things here, but nothing especially new".
