Wheels from Kia Picanto III on Mazda 2: compatible?

No, the centre bore is too small

Same 4x100 PCD, but the centre bore of the wheels from Kia Picanto III (54.1 mm) is smaller than the hub of Mazda 2 (63.4 mm): they will not fit without being re-bored by a professional.

Kia Picanto IIIfrom 2017Mazda 22003–2007
PCD4x1004x108 / 4x100
Centre bore54.1 mm63.4 mm
ThreadM12x1.5Ecrous - 12x1.50
Original wheels 4.5Jx13 ET41
5.5Jx14 ET45
6Jx15 ET51
6.5Jx16 ET51
≈5.5Jx14 ET47
≈5.5Jx14 ET45

≈: width estimated from the original tyre size.

Before fitting the wheels

An identical hub is not enough: offset, width and diameter change the position of the wheel, and larger calipers can touch a smaller wheel. Original wheels often use bolts or nuts with a specific seat: keep the fixings intended for the wheel, with the thread of Mazda 2 (Ecrous - 12x1.50), tightened to the torque shown on its vehicle page. Finally, check that the size is among the approved fitments for your vehicle. This comparison is for guidance only: have the fitting approved by a professional.

And the other way round: wheels from Mazda 2 on Kia Picanto III?