Mitch Trubisky made his third start at quarterback, Najee Harris made his preseason debut at running back and the first-team defense feasted on a Detroit offense that went without starting quarterback Jared Goff.
The resulting 19-9 victory over the Lions on Sunday afternoon at Acrisure Stadium completed the Steelers' preseason at 3-0.
Rosters must be reduced to 53 by 4 p.m. Tuesday.
The regular season opens on Sept. 11 at Cincinnati.
The Steelers opened the scoring on a 10-play, 58-yard drive in 6:14 that included a 38-yard completion to wide receiver Diontae Johnson, an 11-yard run by Harris and three offensive penalties.
Left offensive tackle Dan Moore Jr. was called for holding on first-and-10 from the Lions' 14-yard line. Moore drew a second flag for holding on second-and-8 from the Detroit 12. And left guard Kevin Dotson was whistled for a false start on third-and-18 from the Lions' 22.
The Steelers eventually settled for a 45-yard field goal by kicker Chris Boswell and a 3-0 lead with 3:22 left in the first quarter.
The defense set the table for the Steelers' next two scores, both field goals by Boswell.
Cornerback Cam Sutton's interception and 45-yard return to the Detroit 19 led to a 34-yard field goal by Boswell and a 6-0 lead with 12:32 left in the second quarter.
Inside linebackers Devin Bush and Myles Jack combined to stuff running back Justin Jackson for no gain when the Lions went for it on fourth-and-1 from the Detroit 25.
A second consecutive four-play scoring drive ended with a 38-yard field goal by Boswell and a 9-0 lead with 8:45 left in the first half.
The Steelers had as many first downs as field goals at that juncture.
Harris gained 10 yards on his first four carries, with two attempts resulting in tackles for a loss.
Trubisky was sacked on his first two passing attempts.
He found some rhythm on the Steelers' seventh possession and drove the two-minute offense 92 yards on 10 plays in 1:20 for the game's first touchdown.
Trubisky hit wide receiver George Pickens for 22 yards and tight end Pat Freiermuth for 32 on a march that overcame a holding penalty against right offensive tackle Chukwuma Okorafor and finished on a 6-yard slant to wide receiver Steven Sims. Boswell's extra point gave the Steelers a 16-point advantage 14 seconds before halftime.
Trubisky finished the first half with 15 completions on 19 attempts for 160 yards and a touchdown.
No. 1 pick Kenny Pickett took over at quarterback at the start of the third quarter.
Game action photos from the Week 3 preseason game vs. the Detroit Lions at Acrisure Stadium
His first series ended with a punt on which outside linebacker Derrek Tuszka took over as the long-snapper.
The Lions got on the scoreboard on a 36-yard field goal by kicker Austin Seibert that concluded an eight-play, 68-yard drive in 2:39 with 10:01 left in the third quarter.
Pickett responded by hitting wide receiver Miles Boykin for 29 yards to the Lions' 11 but Boswell's 29-yard field goal attempt was blocked.
He bounced back with a 54-yard effort that ended a 12-play, 44-yard drive in 5:26 that re-established a 16-point lead for the Steelers at 19-3 with 12:59 left in the fourth quarter.
The Lions scored their lone touchdown with 30 seconds remaining on a 5-yard touchdown pass from quarterback David Blough to wide receiver Quintez Cephus (Blough's pass fell incomplete on an attempted two-point conversion).
The Lions recovered the subsequent onside kick but were unable to score again.
Pickett finished 10-for-14 passing for 90 yards.
Mason Rudolph entered at quarterback after the defense stopped the Lions on fourth-and-goal from the 7 with 7:06 left in the fourth.
Johnson sustained a shoulder injury in the first quarter and did not return.
Outside linebacker T.J. Watt exited in the second quarter (knee). Watt was back on the sideline in the second half.
Safety Damontae Kazee (arm) was hurt in the third quarter and didn't return. He came back to the sideline in a sling.