The bank reached its goal after opening to its general customers in less than three hours.
Existing investors with Monzo accounts were eligible to start investing on Monday.
Following the two day window for existing investors (who in previous rounds backed the bank via the Crowdcube platform), Monzo raised a total of £10m from general account holders after just a few short minutes. A further £5m was raised in the next half an hour, getting the firm to 75 per cent of its fundraising target.
The shares are worth just over £7.71, significantly higher than their price in Monzo's last funding round, where they were valued at £2.36. Monzo’s customers can invest up to £2,000 in the bank which can - for some controversially - be funded using Monzo overdrafts.
A recent study by CREALOGIX shows that 14 per cent of UK bank users have at least one mobile-only digital banking account. The most popular digital bank among the 2,000 people surveyed was Monzo.
Luke Lang, co-founder of Crowdcube, said in a statement: “Monzo’s raise, which has been powered by Crowdcube, will undoubtedly spark a new era for crowdfunding as bigger brands with large communities want to emulate Monzo and benefit from the backing of their customers.”