And Kenny Miller secured three points when he fired home a confident spot kick on 83 minutes after Naismith had been brought down in the box by Eggert Jonsson.
The first-half, as expected, turned out to be a nervy affair with the Light Blues under a bit of pressure following Celtic’s last-gasp victory over Hibs.
But in the second the home side turned on the style with Madjid Bougherra, in particular, showing just why he is such a special talent.
Rangers are now eleven points clear at the top of the table and if Celtic fail to beat Dundee United at Tannadice next weekend the Light Blues will be champions.
Kris Boyd and Kevin Thomson returned to the starting eleven for this fixture, the first of the controversial league split.
Thommo took the place of Maurice Edu in the middle of the park while Boyd, who is still looking for his 100th SPL goal for Rangers, joined Kenny Miller in attack.
Smith named a strong team for the visit of Jim Jefferies team who were sixth in the league table prior to today’s fixture.
In defence Steven Whittaker, Bougherra, David Weir and Sasa Papac protected Allan McGregor’s goal having kept a clean sheet against Dundee United on Wednesday night.
And in midfield Steven Davis and Lafferty featured on the right and left flanks respectively with Thomson and McCulloch providing plenty of grit in the engine room.
Rangers started this match positively after a rousing reception from the home support who belted out Tina Turner’s ‘Simply The Best’ as the players appeared from the tunnel.
And after just one minute of play the lively Miller, who worked tirelessly throughout, sprinted through on goal but was marginally offside at the start of the move.
Bougherra then darted down the right wing and having skipped past Lee Wallace his dipping cross was tipped over the bar by MacDonald who was almost got caught out by the swerve on the delivery.
The Jambos, however, were playing with confidence and it was Rangers that clearly had all the pressure on their shoulders.
Craig Thomson on the right wing was enjoying plenty of joy in the opening stages and on seven minutes he darted clear and his cross was headed wide by Obua at McGregor’s near post.
At the other end Kevin Thomson’s ball in from the left was cleared and David Weir’s volley from the edge of the box was skewed high and wide of target.
On 16 minutes Rangers produced an excellent move with Steven Davis feeding it down the right channel to Miller.
His cut back found Boyd with his back to goal but the no.9 slipped as he swiveled on the spot.
This was turning in to a good period of play from Rangers and after Kyle Lafferty had won a corner on the left a McCulloch header from a Thomson corner was punted off the line by Laryea Kingston.
At the 20 minute mark there was an air of tension within Ibrox and the match was ignited by two poor challenges by Obua and Craig Thomson, on Kevin Thomson and Weir, which resulted in bookings for both Hearts players.
The first-half was lacking in any real quality with both teams failing to create any clear cut chances although Lafferty should have done better with a header from Bougherra’s cross with just 60 seconds left.
After the break Rangers went through the gears and on 47 minutes the two Steven’s – Davis and Whittaker – combined but the latter’s cut back was cleared by Zaliukas.
This got the home side off their seats as did a bursting run from Kevin Thomson which saw the midfielder hauled to the turf cynically as Rangers looked to counter.
From the resulting free-kick 40 yards from goal Thomson touched the ball to Papac and the left-back dinked a clever ball in to the box.
Miller was quickest to react and his glancing header produced a stunning save from MacDonald who somehow clawed the ball away from his top corner in front of the Copland Road Stand.
At this stage you started to wonder if this was going to be one of those days for the Gers.
But on 53 minutes the breakthrough finally came and it was Lafferty that was on target.
The big Ulsterman did brilliantly to power a header past MacDonald from a Thomson corner but his Peter Crouch-esque celebration didn’t quite match his finishing on this occasion!
Lafferty was now looking like a new player on the left, darting past his marker with ease but his game was effectively over on 62 minutes when he was clattered by a poor challenge from Ian Black.
The former Inverness Caley Thisle man was booked and despite Lafferty’s best efforts to stay on he was eventually replaced on 69 minutes by Steven Naismith.
Rangers were now in the ascendancy and Thomson’s growing confidence was highlighted when he curled a spectacular shot with his left boot which smashed off the bar before being cleared.
It was a moment of magic from the midfielder but with 18 minutes to go Hearts were still in this intriguing contest.
Nacho Novo was introduced to the game by Walter Smith, who was now in the home dug-out as opposed to his Directors Box seat.
And the Spaniard was instrumental in his side’s second on 83 minutes.
Nacho beat Hearts’ offside trap to sprint clear down the right and his teasing, low cross looked to be finding Naismith.
The sub, however, was pushed to the ground by Jonsson and referee Iain Brines immediately pointed to the spot and issued a red card to the right-back.
Miller took on the responsibility and his powerful penalty beat MacDonald to his left despite the keeper getting a strong hand to the ball.
Chants of ‘Championees’ started around the stadium and with Rangers just needing a point from their four remaining games, regardless of what Celtic do in Tayside next weekend, a title party should now be a formality.