Mansfield will sign Kilmarnock striker Ben Hutchinson, Oxford forward Matt Green and Port Vale midfielder Gary Roberts when the transfer window opens.
Hutchinson, 24, will sign until the end of the season on a free transfer.
Green, 24, has agreed an 18-month contract for an undisclosed fee after a successful loan spell, where he has scored 14 goals in 25 games.
Roberts, also 24, had his contract at Vale terminated and will sign an 18-month deal at Town on 1 January.
Former Middlesbrough, Celtic, Swindon, Dundee and Lincoln striker Hutchinson joined Killie on a six-month deal in the summer and has scored once in five appearances.
Green is Mansfield's top scorer this season following his summer loan move and the clubs agreed a fee in October, although the former Cardiff and Torquay man has just signed personal terms.
Roberts, 24, left Vale earlier on Friday following a second breach of club discipline.
The former Crewe, Yeovil and Rotherham player has left each of his four clubs following disciplinary problems.