Thursday's "We Will Always Love You: A Grammy Salute to Whitney Houston" will air as an hour-long TV special on Nov. 13.
Hudson rocked a pompadour and glittery jacket reminiscent of Houston's stage costumes from the 1980s and belted out a medley of Houston's hits.
"She's just been like this outline, this blueprint for myself," Hudson said.
LL Cool J, Halle Berry, Taraji P. Henson, Usher, CeCe Winans and Yolanda Adams also participated in the musical tribute.
Spears said she's always been "a huge fan" of Houston's.
"I think she's amazing," Spears said. "And I think that her voice is better than God. I just, I love her."
Houston died in February at the age of 48 from accidental drowning complicated by drug use and heart disease.
The Associated Press contributed to this report.