Millwall are close to bringing in Liam Trotter and Shaun Batt after both players had successful loan spells at the club.
Ipswich midfielder Trotter is set to sign a two-year deal after playing a major role in the Lions' charge to promotion from League One.
Trotter, 21, was on the losing side only twice in 26 outings following his arrival in January.
He told the Lions' official website: "I'm very excited and extremely happy to be a Millwall player.
"It's great to be playing regularly and winning games, and I'm confident that we can continue to be successful in the Championship.
"We have a very well organised and disciplined squad here. I'm sure we will improve and I believe we are capable of doing more than just hold our own at the higher level."
Millwall have also agreed terms with Peterborough to sign striker Batt.
The 23-year-old scored on his Lions debut against Southend in January after joining on a three-month loan deal.
He netted a further two goals before making his 18th appearance for the club in the play-off final victory over Swindon last Saturday.
Batt is now set to discuss personal terms with Millwall as Kenny Jackett looks to reinforce his squad for the Championship next season.