Yes, with care — human-grade, shelled, unsalted peanuts are okay as an occasional treat. The risk is aflatoxin, a mold poison that causes liver disease in birds.
What it means for budgies
Because budgies are prone to obesity and fatty tumours, treat peanuts as an occasional, rationed treat rather than a regular food — a little goes a long way for a bird this size. A budgie portion is tiny — a single bite or a little grated amount is plenty.
The full picture on peanuts
Peanuts themselves are not toxic; the danger is Aspergillus mold, which produces aflatoxin and thrives inside peanut shells — especially in bulk bins and bird-feed-grade nuts. Chronic low-dose exposure causes liver disease; a moldy nut can cause acute poisoning. Peanuts are also fatty enough to crowd out better foods.
Human-grade, shelled, unsalted, unflavored only.
Use as occasional training treats, not a daily staple — a half peanut for small birds.
Discard anything discolored, shriveled, or musty-smelling.