Steven Gerrard finally got his midfield wish as Rangers beat the transfer deadline to sign South Africa Bongani Zungu, while Celtic also made a late swoop for AC Milan and Uruguay left-back Diego Laxalt.
Ibrox boss Gerrard has made little secret of his desire to add another option to his engine room but was made to wait until just two hours before Monday's midnight cut-off point to see a long-running transfer saga involving Amiens ace Zungu finally come to fruition.
Gers had been linked with the 27-year-old powerhouse midfielder for much of the summer, with the Light Blues initially quoted a £4million fee.
But in the end Rangers sporting director Ross Wilson has been able to negotiate a season-long loan, with the Light Blues holding an option to make the deal permanent next summer.
There also appears to be further good news for Gerrard with Alfredo Morelos expected to stay at Ibrox despite fresh speculation over his future with an unnamed Serie A club said to have failed in a loan bid for the Colombian.
Celtic also left it late to complete a deal for Laxalt. The 27-year-old flew into Glasgow to complete a season-long deal and was presented to the media just after 9pm.
The former Genoa player has won 24 caps for Uruguay and has been brought in to provide competition for Greg Taylor.
Celtic have sold 20-year-old forward Jack Aitchison to Barnsley. The club's youngest goalscorer, who netted against Motherwell at the age of 16, will be immediately loaned to an English League Two club but has signed a three-year deal with the Yorkshire side.
Aberdeen have re-signed left-back Greg Leigh on a short-term deal following his exit from NAC Breda while former Hamilton keeper Gary Woods has been recruited on loan from Oldham on a short-term basis to provide cover for the injured Tomas Cerny.
The Dons earlier loaned forward Bruce Anderson to Ayr for the season with an option to recall the 22-year-old in January.
Livingston were the first Scottish Premiership club off the mark on transfer deadline day as they took midfielder Josh Mullin back to the Tony Macaroni Arena.
Mullin helped Livi to successive promotions before achieving a personal hat-trick with Ross County and he returns to West Lothian after requesting a move from Dingwall last week.
There was also a departure from Gary Holt's squad as the Lions ripped up Aymen Souda's contract in order to allow the homesick French midfielder to return across the Channel.
County moved quickly to fill the gap by signing 21-year-old Birmingham midfielder Charlie Lakin on a season-long loan. Lakin has made 15 appearances for Blues and played 25 times in a loan spell at Stevenage last season.
Hibernian confirmed the signing of Kyle Magennis from St Mirren on a five-year deal after succeeding with the latest in a series of bids for the midfielder last week.
The Buddies have strengthened their defensive options by bringing in two new signings. First Northern Ireland Under-19 right-back Daniel Finlayson arrived from Rangers on loan with an option to buy at the end of the season, while Coventry's Brandon Mason clinched a season-long loan move to Paisley with just an hour to spare.
Dundee United beat the transfer deadline to sign Scotland striker Marc McNulty on a season-long loan from Reading.
Boss Micky Mellon now hopes to partner the former Hibernian and Livingston poacher with another member of Steve Clarke's squad in Lawrence Shankland.
He told the club's official website: "I'm pleased that we're going to be able to add another international footballer with the qualities that Marc has to the group in order to help us move forward to the Dundee United we all want to see. He's definitely a step in the right direction for us to achieve that.
"Marc's an international player so he'll bring the qualities of a player who has played at the highest level. He's pacey, clever and fantastic in the 18-yard box. You only have to look at his goals-per-game – he scores everywhere he's been.
"We're looking forward to getting him in and working with him with the rest of the group and, hopefully, pushing him as well towards getting back into the Scotland squad on a regular basis."
On Shankland, he said: "There's nothing that I have been told to brace myself for and there really hasn't ever been anything. We are still really keen to continue moving Dundee United forward and Lawrence is a massive part of that. I don't expect anything to happen."
St Johnstone boss Callum Davidson has signed 27-year-old striker Guy Melamed from Israeli Premier League side Maccabi Netanya after earlier moving two forwards on.
John Robertson, 19, has joined Forfar on loan until January while Isaac Olaofe has cut short a temporary move from Millwall by mutual consent after making two substitute appearances in August.
Hearts youngster Anthony McDonald became the latest Gorgie academy recruit to head overseas after joining Spanish outfit Cordoba on a two-year deal. His move comes less than two weeks after Aaron Hickey joined Serie A side Bologna.
