The Republic of Ireland international has been linked with Everton all summer but in true Toffees style it only went through within minutes of the deadline on Monday evening.
The main sticking point was the fee, with Everton seeing two bids rejected – the second very publicly by rent-a-gob Dave Whelan.
However, flush with cash following the sale of Maoruane Fellaini to Manchester United (though the club insist they were never relying on that deal to fund others) terms over a £13million transfer were agreed.
Speaking after finally putting pen-to-paper on his new contract, McCarthy told the club’s website:
"To be honest I am over the moon. The last few hours have been nerve-racking and I am delighted to be here.
"Once I knew Everton were interested there was no going back - I wanted to come here and try and establish myself.
"I worked under the manager for four years at Wigan, they were four brilliant years. I loved every minute of that. I know some of the boys who are here so it was a no-brainer to be honest."
While he is certainly no Felliani, he does represent a player closer to the style of play Roberto Martinez is trying to employ.
Those who know him well are full of praise not just for his ability but his potential.
So while £13million may seem steep now, it may be a worthwhile investment given he is just 22-years-old.
How do you think McCarthy will fit in? have your say below.
More from Royal Blue Mersey:
- Marouane Fellaini thanks Everton fans after Manchester United move
- Marouane Fellaini and Leighton Baines - Replaceable vs. Irreplaceable
- Gareth Barry joins Everton on loan from Manchester City
- Victor Anichebe leaves Everton for West Brom
- Everton sign James McCarthy from Wigan