The album received generally mixed reviews from music critics, and commercially, it proved to be a moderate success. Debuting on February 12, 1994 at number 102 on the Billboard 200, the album reached its peak a week later at number ninety-six, while spending nineteen weeks on the US chart in total. Overseas, the album entered the UK Albums Chart at number thirty-one, but charted for only two weeks there. Other territories included Switzerland (at number thirty-two), Japan (at number sixty-six), Netherlands (at number sixty-nine), and Germany (at number ninety-two).
Four official singles were released from the set, three of which entered the Billboard Hot 100, as well as the UK Singles Chart. All of them became successful on the dance chart, bringing Peniston two additional number one hits on the US Hot Dance Club Songs. In Japan, the album was shortly followed by Remix Collection, which featured alternate versions of songs issued on singles. The album was not accompanied by a worldwide tour.
Thought 'Ya Knew received mainly mixed reviews. In terms of artistic achievement, dancefloor potential or chart performance, the album did not match the success of Peniston's debut album, Finally. Jose F. Promis from Allmusic, however, blamed the record label A&M for marketing the artist to an R&B audience, which he called the "big mistake". Giving the album three (ouf of five stars), he highlighted especially "Hit by Love" anthem as the song closer in spirit to the singer's early dance hits, but he admitted that by that time of the single's release its "steam had worn off". Both critics, Martin Johnson from Chicago Reader and Johnny Huston from Entertainment Weekly agreed that the album's low points occurred on its ballads and that Peniston faltered on slower numbers. (Johnson also added that even Toni Braxton, who redefined the urban contemporary ballad, "would have trouble breathing life into them"). While Huston noticed Patti LaBelle-influenced vocal stylings (on "Through Those Doors"), Johnson recalled young Chaka Khan and stressed the pungent lower registers of the singer's voice (on "Searchin'").People magazine found the album's problem in Peniston's big-time pop success and her new need to be seen more serious than just a dance-music artist. Calling ballads "the ballads from hell", the magazine reproached that all the slow stuff did was focus on Peniston's vocal limitations.
On February 5, 1994 the album entered at number thirty-one (its peak) in the UK Albums Chart, spending two weeks on the chart. Followed by the Oricon list on February 10, Peniston received her first and her only album chart appearance to date in Japan, at number sixty-six (two charting weeks in total) After two weeks since its release, the album entered the US Billboard 200 at number one-hundred-two on February 12, 1994. Peaking its top the following week, at number ninety-six on February 19 (nineteen weeks in the chart). On the component, US Top R&B/Hip-Hop Albums chart, the album climbed to number twenty (being present for thirty-four weeks in the chart. Later on, the album would be classified as the seventy-first best R&B selling set of 1994.) In Dutch MegaCharts, the record started its five weeks long run on February 19, topping its third week at number sixty-nine. In addition, the album cracked the Swiss Music Charts on February 20, peaking on March 6 at number thirty-two (three weeks in the chart). And on February 28 also the German Media Control Charts, reaching at number ninety-two (with three weeks in the chart).