Mona Barthel showed her mettle to Auckland audiences in 2012, taking out Jelena Dokic before losing a tight battle against top seed Sabine Lisicki. She continued her good form onto Hobart, where as a qualifier she won her first title with wins over Angelique Kerber and Yanina Wickmayer.

At the 2012 Australian Open, Barthel reached the third round, where she lost to eventual champ Victoria Azarenka. The two faced off again in Doha and Indian Wells, and in the latter Barthel battled hard and narrowly lost to the world #1 4–6, 7–6(7–4), 6–7(6–8).

The German neared closer to the top 30 with quarterfinal berth at the E-Boks Sony Ericsson Open at Copenhagen where she held match points against Kerber before losing 7-5 in the third set.

Azarenka would prove the spoiler again in Stuttgart, and again Barthel frustrated the world number one, losing again in three tight sets 4–6, 7–6(7–3), 5–7.

The rest of Barthel's season included a semifinal run in the Sony Swedish Open and a narrow loss to Agnieszka Radwanska in Montreal, a match in which she held a match point.

Barthel, whose idol while growing up was German great Steffi Graf, has sporting success is in her blood, with father Wolfgang having been a European shot put champion.