In 2015, she finished second in individual pursuit and points race at the European Track Championships.

In particular, she took part in many Semaines fédérale internationale de cyclotourisme, a massive touring cycling event.

At the age of 12, she began to compete in the Union française des œuvres laïques d'éducation physique (UFOLEP).

In June the same year, she participated in the French track championship at Hyères, where she won the points race.

Two years later, she earned her Brevet de Technicien Supérieur (BTS) of engineering assistance in Armentières.

[3] At the Grand Prix Elsy Jacobs, a top-level international women's stage race, she finished seventh in the general classification.

[16] The end of the year brought fewer results but allowed Delzenne to collect experience: she participated in the Lotto Belisol Belgium Tour, the GP de Plouay, the Giro della Toscana and the World Championship road race in Florence.

[23] She participated in the Ronde van Drenthe race of the UCI Women's Road World Cup, in Le Samyn des Dames, Gent–Wevelgem and the GP Dottignies.

[11] At the beginning of May, she finished fourth in the Ronde van Overijssel, where Lisa Brennauer from her team won.

She was then fifth in the general classification[26] Her work as teammate did not allow her to keep this place in a race where all stages finished by a bunch sprint.

[27][28] At the national championship, Delzenne finished, once again, in fourth place in the time trial, one second behind Aude Biannic.

[31] In July, she participated in the Thüringen Rundfahrt der Frauen and helped her teammates Evelyn Stevens and Lisa Brennauer to finish respectively first and third in the general classification.

[42] After the winter break, she competed at the International Belgian Open and won the points race.

She concentrated on the track at the beginning of the season and participated in the Cali round of the World Cup.

In February, she was selected for the track world championships in individual and team pursuit, as also for the points race.

She finished fifth in the time trial and then also fifth in the road race, where she was unable to follow the attack from Pauline Ferrand-Prévot.

The week after took place the National Track Championships where she won 3 titles: individual pursuit, points race and scrath.

[57][58] In the beginning of March, she took part to the World Track Championships in individual pursuit and points race.

She is for instance in the leading group during the first stage of Festival Luxembourgeois du cyclisme féminin Elsy Jacobs.

She helped Lotte Kopecky during her victory at Trofee Maarten Wynants and confirmed at the middle of May, with a long solo breakaway with the win at the end, in a national Belgian race.

In the end of May, she realized very good performances during one week-end: on Friday, she finished second of la Classique Morbihan won from Christine Majerus ; on Saturday, she finished third of Grand Prix de Plumelec-Morbihan Dames ; eventually on Sunday, she is third in the sprint at Gooik–Geraardsbergen–Gooik.

[63] In June, the French Cycling federation announced that Élise Delzenne is substitute for the olympic road race.

[71][72] During the French National Track Championship, she defende with success her title in individual pursuit.

Two weeks later, at the World Cup in Glasgow, she won the scratch race and finished second of the individual pursuit.

[75][76] In 2017, she focused on the track in the beginning of the year with the participation to the World cups in Cali and Los Angeles.

[79] At Festival luxembourgeois du cyclisme féminin Elsy Jacobs, on the second stage, Élise Delzenne was present in the field that sprint for the victory.

She launched her sprint from far, but could resist to the come back of Eugenia Bujak and Christine Majerus to obtain the victory.

[82] During the road race, she made a breakaway with Audrey Cordon-Ragot, but the field reacted and caught them.

She was then eighth of the time trial and second of the fourth stage beaten from Nancy van den Burg.

[89] At the World Road championship, she took a breakaway with Janneke Ensing, Amanda Spratt and Danielle King with two rounds to go.