The 25-year-old Netherlands international was confirmed as a Magpies player on Monday, having signed a six-year-contract from Ajax for a reported fee of £11m.
Pardew is "overjoyed" to welcome the versatile attacker to St James' Park, and is positive that he can provide the creativity that Newcastle were missing offensively as they failed to find the net in nine out of 12 matches towards the end of last campaign.
He told the club's official website: "We are absolutely overjoyed to bring Siem to the club because he will give us intelligence in the final third and create goalscoring situations, which we lacked towards the end of last season.
"It is a big signing for this club. Siem brings massive experience from Ajax, I think our fans are going to enjoy the way he plays and I cannot wait to start working with him."
De Jong represents Newcastle's first significant permanent acquisition since the summer of 2012.