Steven Gerrard’s side endured a frustrating evening against their obdurate Polish visitors, having drawn the first leg 0-0 in Warsaw last week.
However, in a game of few clear chances, Morelos headed in Jordan Jones’ cross to seal Rangers’ place in the group stage alongside Celtic for the second consecutive season.
The draw will take place at 12:00 BST on Friday.
Rangers toiled for much of the game inside a febrile Ibrox, a section of which was closed after the club were charged by UEFA for sectarian singing by fans during the first qualifying round win over St Joseph’s.
The club confirmed on Wednesday that they will not take tickets for their first away match in the group stages after being given a second UEFA charge for more “racist behaviour” in the first leg against Legia.
Rangers will discover their fate at a hearing on Friday, and face the prospect of either playing their next home game behind closed doors or being banned from taking fans to their next away fixture.
Morelos finally claims his prize
Rangers lacked a clinical, final touch from the start. An unmarked Morelos jabbed Ryan Jack’s right-wing cross wide from a promising position after 10 minutes and would spurn another chance before the half was out.
This time, the Colombian led a counter attack before cutting inside and firing a shot towards goal. However, his shot through a sea of Legia defenders bounced tamely towards goalkeeper Radoslaw Majecki.
The visitors tried to take advantage of a blunt and ineffective Rangers performance when Luquinhas latched on to a loose ball just after the half-hour , but the forward’s own attempt mirrored Morelos’ chance with a shot straight at Allan McGregor.
On the stroke of half time towering midfielder Carlos Cafu met a corner to knock the ball just wide of the Rangers’ back post, but it was the home side that went in to the break cursing their missed chances.
If poor luck dogged Rangers’ first half, it was all to evident in the second period, too, when the first action of the half saw left-back Borna Barisic go down injured after colliding with Nikola Katic.
The Croatian defender was eventually forced to come off, but not before Morelos misjudged another clear header in the 65th minute, following a perfectly weighted cross from James Tavernier.
The game was temporarily halted during the second half after smoke from flares set off by the raucous Legia fans clouded the pitch. And, against the backdrop of an increasingly agitated home crowd and an increasingly rambunctious away section, Morelos continued to hunt for the all-important goal.
With 20 minutes to play, the Colombian curled a deflected shot just wide, then a few minutes later he met a Tavernier cross with an audacious volley straight at the goalkeeper. Chances kept appearing, but the Rangers forward continued to miss the target.
The home side’s continued attacking intent was almost all in vain when Jaroslaw Niezgoda skipped inside Connor Goldson with minutes of the 90 remaining, but his effort was saved by an alert McGregor.
The breakthrough finally came in the 91st minute. Jones cut inside from the left and dug out a back-post cross towards Morelos, who connected cleanly and watched the ball nestle just inside the back post.
It wasn’t pretty or impressive but it was more than enough.
- 2TavernierBooked at 70mins
- 19KaticBooked at 80mins
- 31BarisicBooked at 60minsSubstituted forFlanaganat 64′minutes
- 37ArfieldSubstituted forJonesat 72′minutesBooked at 90mins
- 11OjoSubstituted forKamaraat 90+5′minutes
- 41StolarskiBooked at 38minsSubstituted forNagyat 73′minutes
- 5LewczukBooked at 90mins
- 16Martins Rocha
- 26Ribeiro Dias
- 24Soares Martins
- 82Lima Linhares
- 99KulenovicSubstituted forNiezgodaat 56′minutes
- 9Daniel López Huesca
- Slavko Vincic