Cardiff council has claimed to be the fastest local authority in Wales to issue one of the new £75 on-the-spot litter fines.
Cardiff residents now face a litter crackdown
The Welsh Assembly Government has trebled the fixed penalty for litter and dog fouling from £25, with the new fines coming into force from 1 April.
Cardiff says it issued its first fine at 0715 BST - to a resident in the Grangetown area for putting their rubbish out on the wrong day.
And pet owners have also been warned about a crackdown on dog-fouling.
Councillor Phil Robinson, deputy leader, said: "People have to take responsibility for their own waste. This includes those that litter the streets or choose not to put their rubbish out on the kerbside on the correct day for collection"
'Taken a lead'
"This increased fine will hopefully help to act as an added deterrent to stop those that are offending."
The Cardiff litter enforcement team has already issued 1,600 fines at the £25 rate and Mr Robinson said the speed of Thursday's action "demonstrates that we have taken a lead in exacting the £75 penalty without delay."
The authority has also warned that dog-owners caught allowing their pets to foul footpaths or parks will be given the choice of paying the £75 or going to court.
Patrols are being undertaken of city parks by dog wardens and park rangers.
The assembly agreed the tougher approach last month, with Environment Minister Carwyn Jones warning that the issue could not be taken lightly.
He said: "People need to realise that dog-fouling and fly-tipping also have an economic impact in terms of attracting inward investment and tourism."