Della Monica started skating pairs in 2007 when she teamed up with Yannick Kocon, who was also a single skater until then. They are the 2009 and 2010 Italian national champions. They represented Italy at the 2010 Winter Olympics. Their partnership ended in January 2011 — Della Monica had a chronic inflammation in her left knee and her recovery time was uncertain.
Della Monica and her partner began the 2017–18 season with silver medals at Lombardia Trophy and Finlandia Trophy. Competing again at the Cup of China, they placed fourth. At the Internationaux de France, they placed third, winning their first Grand Prix bronze medal. Della Monica pronounced herself "really happy with our performance." Della Monica/Guarise won their third straight national title, followed by a sixth-place finish at Europeans. Competing at their second Olympic Games in Pyeongchang, South Korea, they placed tenth. The season concluded at the 2018 World Championships in Milan, where they placed fifth overall.
2018–19 season
Their 2018–19 season began again at Lombardia Trophy, where they own the bronze medal. Turning to the Grand Prix series, they won silver at the 2018 Grand Prix of Helsinki. Della Monica commented that "this is our first silver medal on the Grand Prix. Last year we won our first medal, a bronze, so we are happy that we improved. Next time it maybe will be gold, who knows. It shows that we are on the right track." They won a second silver medal at the 2018 Rostelecom Cup, becoming the first Italian pair team to qualify for the Grand Prix Final, a goal they had set for themselves at the beginning of the year. They placed fifth at the Final, after multiple falls and popped jumps. After winning their fourth consecutive national title, Della Monica/Guarise competed at the 2019 European Championships. They placed third in the short program, 0.12 points ahead of Aleksandra Boikova / Dmitrii Kozlovskii of Russia, and were awarded a small bronze medal for the result. In the free skate both teams made errors, with Della Monica putting a hand down on their three-jump combination, and a result finished fourth in the free skate and fourth overall, 0.14 points behind Boikova/Kozlovskii. Guarise said they were "a little bit disappointed actually, because we gave everything we had. It maybe wasn’t 100 percent, but I think it was very good." At the 2019 World Championships, Guarise collided with French skater Vanessa James in the warmup for the short program, which shook up both skaters. He then doubled his jump attempt, causing them to place eighth in the short. In the free skate the team had multiple errors, finishing seventh there, and eighth overall. Guarise reported that the aftereffects of the collision had been more of a problem than he initially believed. Della Monica/Guarise concluded the season at the 2019 World Team Trophy as part of Team Italy, which finished sixth out of sixth teams.
2019–20 season
Della Monica dislocated her shoulder during the summer, delaying the team's training significantly. They returned to competition at the 2019 Icelab International in Italy, taking the silver medal, a week before their first Grand Prix. At the 2019 Cup of China, they placed fourth. At the 2019 NHK Trophy, Della Monica/Guarise placed eighth.
