"On a Sunday" represented Romania in the Eurovision Song Contest 2019 in Tel Aviv, Israel, after winning the pre-selection show Selecția Națională.

The show was the first one in Romania's Eurovision participation history to be significantly invested in by the Romanian Television (TVR), with costs amounting to a reported 100,000 euros.

The track was met with mixed reviews from music critics upon its release, with some praising its production, contemporary nature and Peony's vocal delivery.

To promote "On a Sunday", Peony performed the song on multiple radio and television stations in Romania, as well as on Eurovision-related occasions in the Netherlands and Spain.

Directed by Petre Năstase at Casa Monteoru in Bucharest, the video shows Peony wearing multiple outfits while investigating a haunted house.

Ester Peony gained online recognition in 2014 for covering songs on YouTube, leading to a record deal with a Romanian label.

[6] "On a Sunday" is a mid-tempo blues, R&B, soul and 2000s-influenced "dark" electropop ballad backed by percussion, "Western" guitar, "stuttering" synthesizers and "driving" trance beats.

[11] For the purpose of Peony's Eurovision Song Contest 2019 participation, "On a Sunday" was remastered, undergoing "structural changes [...] in [its] latter portions", leading to a "harsher beat in some parts".

Julian Geiser of Wiwibloggs wrote that the song had "a sultry, standout quality",[16] while Pinzon of the same publication labelled it as "thoroughly contemporary" with a "universal appeal".

[10] Jonathan Currinn, writing for CelebMix, praised Peony's emotional and "classy" vocal delivery, but found the track to be "somewhat disappointing lyrically and rhythmically".

[17] Due to accusations of plagiarising the American folk song "The Wayfaring Stranger", the Romanian Television (TVR) decided to set up a commission to analyze "On a Sunday" in February 2019.

[18] By late February 2019, filming for an accompanying music video for "On a Sunday" had been completed, conducted by director Petre Năstase at Casa Monteoru in Bucharest, Romania.

The clip was uploaded to Cat Music's official YouTube channel on 10 March 2019 and shows Peony "imprisoned in a deserted house".

[12][13][20] In an interview, Năstase explained his vision for the clip: "The song is a story of a toxic relationship, so we created a character that enters a mansion which [...] is haunted by various spirits".

[22] Writing for Wiwibloggs, William Lee Adams echoed Van Lith's thought and went on to compare the mansion to the one in the Netflix series The Haunting of Hill House due to its "derelict walls and eerie destruction".

Adams noted that the video was "bold and just a little brash", as well as "intoxicating with marine life floating in the sky and mirrors reflecting all manner of madness".

[23] For further promotion, Peony performed "On a Sunday" live during O melodie pentru Europa 2019 on 2 March, Moldova's national final to select their entrant for the Eurovision Song Contest 2019.

[16] In more mixed reviews, Currinn of CelebMix wrote that "the stage production [...] certainly does need some work",[17] while Thomas Ling from Radio Times found the performance "memorable", yet called certain aspects "awkward".

[50] 2019 marked the first time that there was a specific emphasis being put on Romania's staging and special effects in its contest history, with TVR's budget for the aforementioned amounting to circa 100,000 euros.

The accompanying dancers enact a battle between good and evil which is visually amplified by the presentation of water, fire and various dark graphics on the LED screens, as well as through pyrotechnics.

During a large amount of the performance, Peony sits on a red armchair, with the dancers advancing to the center of the stage throughout the track's first verse and joining her around the refrain.

The show ends with a brighter stage in comparison to the beginning and shots of peonies blooming from scorched earth in the background, symbolizing a "hopeful future".