The Lady Pies are preparing for their second season in The FA WSL which begins this spring and the additions to Rick Passmoor’s squad will be seen as a real boost.
Experienced defender Bassett, who has 43 caps for the Lionesses, joins from Chelsea Ladies and the 31-year-old has signed a three year contract at Meadow Lane.
She’s joined at the Midlands club by attacker Williams, 26, who also links up from Chelsea Ladies where she scored seven goals in 14 WSL appearances last season.
Greenwood arrives at the club from Everton Ladies, where the full-back began her career in their Centre Of Excellence. A regular for England in various development teams, the 21-year-old made her senior bow in last year’s Cyprus Cup.
And England U23s striker Jess Sigsworth completes County’s swoop, joining from her hometown club Doncaster Rovers Belles where she bagged eight goals in WSL 2 last season.
Speaking about the new additions to his squad, County boss Passmoor said: "These are four players with international pedigree, who all add something very valuable to our squad.
"Laura has a host of experience behind her in the women’s game, at both the top domestic level and international level and that will benefit everyone in our squad, as much as they have qualities that will benefit Laura.
"Alex has a lot of promise behind her, promise that she has already shown at the top international level and we hope she will continue to develop here at Notts County and become a top international player. There’s a hunger and desire to do that.
"Then you’ve got Jess who is still progressing through the international age groups and has already been recognised at U23 age level, despite only being 19 at the time.
"Rachel’s proved her quality at this level since the league started and she is a fantastic addition to our squad. She’s a versatile player who adds real quality.”
County chief executive Luke Negus-Hill added: "Last year was our first year in the league and I think we can be proud of how we performed, but we’ve got ambitions and desires to compete right at the top.
"The signing of international players into this football club shows our ambition and we’re delighted to have them all here at Notts County."