The Haverfordwest-born player’s victory over Germany’s Miranda Wilson made her the first Welsh woman to reach the second round of a BWF World Tour Super 750 singles tournament.
Hart, who made her Wales debut in 2009, triumphed 21-16, 21-13 in 31 minutes at the Odense Sports Park.
“I haven’t played competitively now for seven months now due to COVID-19 so to be back on court was exciting, but a little bit nerve-wracking,” said Hart.
“I’m really pleased to see that my training throughout lockdown has gone well.”
Hart’s reward for her victory is a tough match in the last 16 round in Denmark.
The Loughborough-based player will face Japan’s No 2 seed Nozomi Okuhara on Thursday.
She added: “The match against Okuhara will be a great experience for me as I’ll be playing one of the best players in the world. I’m excited for the challenge.”
Okuhara progressed after a 21-7, 21-19 victory over Scotland’s Kirsty Gilmour.