For her role debut as Imogene in Bellini's Il pirata at the Teatro alla Scala in June 2018, the first production of the piece after a legendary 1958 staging with Maria Callas as Imogene the press proclaimed that her performance would "surely see Yoncheva enter La Scala's hall of fame alongside Callas".

Yoncheva began the 2018/19 season performing the title role of Médée in a staging at Staatsoper Berlin conducted by Daniel Barenboim.

In the spring of 2019, Sonya Yoncheva announced that she was expecting her second child in the coming fall[18] as a result of which she did not perform from mid July to November 2019.

In the 2019/20 season, she performed Mimì in La bohème at the Royal Opera House Covent Garden, the title role of Médée at the Staatsoper Berlin and as Imogene in Il pirata to the Teatro Real in Madrid.

[19] In spring 2020, Yoncheva returned to the stage after the first European lockdown as the soprano soloist of Ludwig van Beethoven's 9th Symphony at the Victoria Hall in Geneva, telecast by Arte.

In summer 2020, Sonya Yoncheva and Rolex announced a concert series in aid of musicians affected by the pandemic and the ongoing cancellations.

Yoncheva was the host of the "Perpetual Music" concert at the Staatsoper Unter den Linden in Berlin in September, featuring 14 singers and instrumentalists.

[20] [21] Engagements until the end of 2020 included solo concerts to open the season of the Würth Philharmoniker and the Antwerp Symphony Orchestra, the title role of Tosca at the Bayerische Staatsoper, the Season Inauguration Gala A Riveder le Stelle of the Teatro alla Scala and a Christmas concert hosted by the German president Frank-Walter Steinmeier and telecast by ZDF.

With the NOSPR led by her husband Domingo Hindoyan, Yoncheva sang Henri Duparc "L'Invitation Au Voyage" in Katowice, before starring in the title role of Tosca at the Wiener Staatsoper.

Sonya Yoncheva's busy summer season also included Stephana in Umberto Giordano rarity Siberia at the Maggio Musicale in Florence, a production of La traviata at the Arena di Verona that was recorded for telecasts on ZDF and 3sat, recitals and concerts in Toulouse, Munich, Baden-Baden, Ljubljana, Montpellier, Sofia, Bucharest and the Salzburg Festival.

In the Fall, she made her role debut as Puccini's Manon Lescaut at the Staatsoper Hamburg, returned to Zürich as Tosca, to the Staatsoper Unter den Linden as Mimi in La bohème and appeared in more solo concerts and recitals in Paris, Aarhus, Bucharest, Genève, Athens, Budapest, Barcelona, Moscow and at the Teatro alla Scala.

Concerts and recitals led her to Montréal, Sofia, Düsseldorf, Salzburg, Baden-Baden, Varna, Tokyo, Buenos Aires, Montevideo, Bordeaux, Katowice, Berlin and Liverpool.

The first season features singers such as Freddie De Tommaso, Jakub Józef Orliński, Fatma Said, Elsa Dreisig, Clémentine Margaine and Yoncheva herself.

In 2023, Sonya Yoncheva received the title of Doctor Honoris Causa from the Academy of Music, Dance and Visual Arts of her native town of Plovdiv.