The President-elect was spotted Tuesday in Wilmington, DE, popping into the Queen Theater to announce new cabinet members, and he was dressed to the nines in his usual navy blue suit ... now accessorized with a walking boot on his right foot.

Doesn't look like the boot was giving JB much trouble ... after exiting his SUV (without assistance) he struck a pose, lifting the boot pretty high, almost like a soldier. When asked how he's feeling, he flashed a thumbs up.

By the looks of it, Biden's probably gonna be just fine ... a vast improvement from how fragile he looked limping out of his doctor's office over the weekend.

Of course, that's not to downplay the seriousness of his injury -- remember, his doctor said he suffered a hairline fracture in his middle foot area when he took a tumble playing with his German shepherd, Major.