Bynes, 27, was charged last year with marijuana possession, evidence tampering and reckless endangerment after police said she threw a bong out of the window of her Manhattan apartment.
However, TMZ cited unnamed law-enforcement sources as saying the case will be resolved Friday in court through a legal maneuver known as adjournment in contemplation of dismissal.
While Bynes will not enter a plea, the charges will be formally dropped if she stays out of trouble for the next six months, the celebrity news website said.
Bynes has been living with her parents in California after months of inpatient treatment for bipolar disorder and schizophrenia.
The actress was arrested multiple times since April 2012 and has been accused of driving while intoxicated, hit-and-run and driving with a suspended license, in addition to the alleged bong-tossing offenses.
Bynes is the former star of the sketch comedy series, "The Amanda Show." Her film credits include "What a Girl Wants," "She's the Man" and "Hairspray."