Yes! Heat pumps are really popular in the Nordics (where it’s pretty cold), which shows they work well even when it’s below 0.
They can work in extremely cold temperatures, as low as -20 °C. When it is very cold outside, the heat pump can’t extract quite as much energy from the atmosphere as usual – which means it has to use a bit more electricity, or in other words is a bit less efficient - but your home will still be able to get to warm, cosy temperatures.
It’s a bit like a gas boiler - when it’s colder, you’ll burn more gas. We see temperatures below -10°C only a few days per year, and even at these temperatures, heat pumps still function more efficiently than gas boilers do.