The 1977 Firebird received a facelift that featured four rectangular headlamps. The shaker scoop was also revised for this year, with the early 1977-built T/As coming with off-center, lower-profile shaker scoops. The Formula hood was changed for the last time for the second generation with a much lower profile. The snowflake wheel became an option for all Firebirds and was standard with the Y82 appearance package, although it could be replaced with Rally II wheels as a credit option.

For the Esprit, an optional appearance package RPO W60 called the "Skybird appearance package" became available, featuring an all blue exterior and interior. This package was originally slated to be called the "Bluebird" similar to the "Yellowbird" and "Redbird" packages to follow in the upcoming model years, but the name was already in use for a company that produced school buses.

In 1977, General Motors began to source a larger selection of V8 engines to supply in the lower model Firebirds, and the Oldsmobile 350/403 V8, as well as the Chevrolet 305/350 V8, became options for the Firebird, Esprit, and Formula after June 1977. Previously, the Chevrolet inline-six was the only outsourced engine in a Firebird. Pontiac made the 301 (4.9 L) V8 available for order in the lower Firebird models, but due to such high demand and popularity, they removed it's availability from the Firebird model to allow enough 301 engines for the other Pontiac lines. It was re-introduced as an option in 1979 as production for the 400 ceased and tooling was converted over to the 301.

The Trans Am had now three different engine options, the standard Pontiac L78 400, the optional extra cost Pontiac W72 400, and the Oldsmobile-sourced L80 403. 1977 also saw the cubic inch metrics on the shaker dropped in favor of the displacement of the cylinders. The shakers had a "6.6 Litre" decal for all L78 Pontiac 400 and L80 Oldsmobile 403 engines. Only the optional W72 Pontiac 400 received the "T/A 6.6" decal.

As Pontiac had discontinued the 455 in the previous model year, a modified 400 Pontiac V8 dubbed the "T/A 6.6" RPO W72 with a single four-barrel 800CFM Rochester Quadrajet carburettor rated at 200 bhp (203 PS; 149 kW) at 3,600 rpm and a maximum torque of 325 lb⋅ft (441 N⋅m) at 2,400 rpm, as opposed to the regular "6.6 Litre" 400 (RPO L78) rated at 180 hp (134 kW). The T/A 6.6 equipped engines had chrome valve covers, while the base 400 engines had painted valve covers. For 1977, the W72 shared the same air cleaner and shared the same 500577 cast block as the L78, but received the 6x4 heads, whereas the L78 only received the 6x8 heads. The 6x4 heads were used on early Pontiac 350 blocks that helped increase the compression, and also had hardened valve seats for a higher RPM operating range.
The Oldsmobile 403 was implemented as the 400 Pontiac could not satisfy emissions requirements for high-altitude states and California. Wanting to still offer a 6.6 litre option for the Trans Am, the 403 Olds was seen as a suitable replacement as when equipped with an A.I.R emissions system, it could satisfy the emissions criteria for these states and still offer the power ratings expected of the Trans Am. The L80 Oldsmobile 403 V8 had slightly more power than the standard L78 Pontiac 400 at 185 hp (138 kW) and offered the same low-end torque of 320 lb⋅ft (430 N⋅m) at a more useable operating range of 2,200rpm.

From 1977 to 1981, the Firebird used four square headlamps, while the Camaro continued to retain the two round headlights that had been shared by both second-generation designs. The 1977 Trans-Am special edition became famous after being featured in Smokey and the Bandit. The 1980 turbo model was used for Smokey and the Bandit II.