The startups selected come from across the financial services sector, representing businesses in areas such as payment solutions, financial inclusion, Open Banking innovation, SME lending and artificial intelligence.
New figures released today as part of the programme showed the UK's fintech sector has raised $19bn in investment in 2018 until the end of August.
In July, it was revealed that the UK scored more fintech investment than any other country globally in the first six months of the year, beating both the US and China to the top spot.
Over the five-month programme, the 20 startups will work with fintech entrepreneurs across the UK through insight sessions into challenges they might face as they scale. Additionally, the programme will conclude with a trip to the US in order to help the startups continue their progress internationally.
Richard Theo, Wealthify chief and fintech envoy for Wales, said what remains to be seen is whether a so-called unicorn - a company valued at $1bn or more - exists within the 20 startups.
The UK has numerous unicorns to date, and was recently crowned the unicorn capital of Europe after it emerged that it has more unicorn startups than the next two highest countries combined.
Economic secretary to the Treasury John Glen said: "Our vibrant fintech sector continues to go from strength to strength, and it’s no wonder that UK fintech has received more investment so far this year than US fintech.
"I’m thrilled to see Tech Nation’s fintech programme launch with such a strong cohort of dynamic young companies - I have no doubt they’re destined for amazing things."