My son worked part-time and I am claiming him as my dependent. Where do I enter his income on my tax return? I don't see it anywhere in TurboTax to enter his income.

You do NOT enter his wages on your return which is why you cannot find a place to enter it. If he is required to file a return it is reported on his own return.

You do not report his income on your return*. If it has to be reported, at all, it goes on his own return. If your dependent child is under age 19 (or under 24 if a full time student), he or she must file a tax return for 2022 if he had any of the following:

1.          Total income (wages, salaries, taxable scholarship etc.) of more than $12,950 (2022).
2.          Unearned income (interest, dividends, capital gains, unemployment, taxable portion of 529 distribution) of more than $1150 (2022)
3.          Unearned income over $400 (2022) and gross income of more than $1150 (2022)
4.          Household employee income (e.g. baby sitting, lawn mowing) over $2300 ($12,950 if under age 18)
5.          Other self employment income over $432, including money on a form 1099-NEC

Even if he had less, he is allowed to file if he needs to get back income tax withholding. He cannot get back social security or Medicare tax withholding.

In TurboTax, he indicates that somebody else can claim him as a dependent, at the personal information section.

*If his only income is from interest and dividends, Alaska PFD or capital gains distributions shown on a 1099-DIV, there is a provision for entering it on your return, using form 8814.