Norwich have signed defenders Ignasi Miquel and Jos Hooiveld, as well as Swindon midfielder Louis Thompson.
Arsenal's Miquel, 21, has signed a three-year deal at Carrow Road for an undisclosed fee with an option for a further 12 months.
Dutchman Hooiveld, 31, arrives on a season-long loan from Southampton.
Meanwhile Thompson, 19, will be loaned straight back to League One side Swindon for the rest of the season as part of his three-year deal.
He joins the Canaries for a undisclosed fee, thought to be around £600,000, which is set to rise to £1.3m, according to BBC Wiltshire.
Thompson has made 44 appearances for Swindon, where he came through the academy system along with his brother, Nathan, who is captain at the County Ground.
Miquel spent last season out on loan at Leicester City and has played five times in the Premier League for the Gunners.
Hooiveld has been with Southampton since 2011 and has made 77 appearances for the club.