The Venezuelan international’s move is a straight-swap for Gayle – although the Magpies were ordered to pay a £2 million fee to secure Rondon – ending a long drawn-out transfer saga.
Rondon’s West Brom contract expires at the end of the season and that is a possible reason why Newcastle were unwilling to pay his £16.5 million release clause, much to the clear discontent of manager Rafael Benitez.
Instead, Benitez reluctantly chose to part with Gayle. However, it is believed the two clubs have not inserted a potential buyout clause for the attacker - so he will return to St James' Park at the end of the campaign.
The former Malaga striker, who becomes Newcastle’s sixth summer signing, will wear the coveted number nine shirt after it was vacated by Gayle, and will go straight into Benitez’s squad for their Premier League opener against Tottenham Hotspur on Saturday.
Rondon - 'It's an honour'
Rondon labelled his move to the North East as an "honour" and is "excited to get started". He added: "The clubs were talking for a long time and now I'm focused on the season to help my teammates to get the points to do well this season."
The 29-year-old believes Newcastle "is one of the biggest clubs in the Premier League" and pointed towards Benitez as a key factor in the move: "I knew about the interest of the gaffer, so I'm happy to be here."
Benitez - 'Salomon knows Premier League well'
Benitez highlighted Rondon's top-flight experience as a big reason why he chased his signature all summer. He said: "When we were looking for options up front, we knew how important experience would be. Salomón has been in the Premier League for a while and he knows how demanding it is."
The Magpies confirmed the signing of Yoshinori Mutō last week from Mainz 05, and Benitez said him and Rondon gives his side a "different options" by improving "the competition between the strikers, which is always positive for the team."
Busy few days ahead… hopefully
Following what has been another frustrating summer on Tyneside with owner Mike Ashley currently sitting healthy with a £24 million profit just from player sales, Benitez has not hidden his extreme disappointment and has called for the club to strengthen before Thursday’s deadline.
The Chronicle reported at the weekend that after Rondon’s arrival, Benitez was expecting at least two more signings. Moves for Paris Saint Germain left-back Stanley N’Soki and Swansea City centre-half Federico Fernandez have been heavily touted, but whether those are the two to arrive is unclear.
What is for certain though, Benitez feels he has been granted the bare minimum in order to improve his squad, and now knows his ambition for the Magpies is not matched by the club’s hierarchy.
Ideally, Benitez would have liked both Rondon and Gayle but is instead left with Joselu as the club's only backup striker. At most clubs, that wouldn't be too much to ask but under a tight regime such as Ashley's, it just is not possible.