Frederiksen was one of just 14 other heads of state to so far hold a bilateral phone call with Johnson.
Johnson has so far spoken to just four EU leaders: Frederiksen, Sweden's Stefan Löfven, Greece's Prime Minister Kyriakos Mitsotakis, and Prime Minister Giuseppe Conte of Italy.
According to a press release issued on Wednesday by the UK's Prime Minister's Office, the two leaders discussed the UK's bid to host COP26, an important international climate conference to be held in November next year, when they held a bilateral phone call on Saturday.
“They… agreed to continue to work together to tackle climate change. They also spoke about threats to biodiversity and action we could take together on this issue,” the release said.
Frederiksen was elected on the back of ambitious green pledges after the environment became the most important issue int he campaign leading up to Denmark's June poll.
In an agreement struck with its allied parties, Frederiksen's government has pledged to introduce binding decarbonisation goals and tighten its 2030 target to reduce emissions below the 1990 level from 40 percent to 70 percent.
According to the statement, Frederiksen told Johnson she hoped that the two countries could remain close allies even if the UK leaves the European Union on October 31, as Johnson hopes.
“The leaders welcomed the strength of our bilateral relationship and committed to build on this once the UK leaves the EU,” the UK's Prime Minister's office said in a statement issued on Wednesday.
Frederiksen also discussed the Nato Leaders’ Meeting which the UK will host in London in December.