The relatively short sanction means the 31-year-old will be clear to play in the World Cup in September.
The Rugby Football Union (RFU) judged his actions a mid-range offence but halved the normal ban of 18 weeks after Cueto gave "compelling mitigation".
Cueto, already been banned by his club Sale, will be free to play on 7 June.
The incident occured during the Sharks' 53-24 Premiership defeat by Northamptonon 2 April.
Cueto's ban was back-dated to 4 April, the day he was handed a six-week internal suspension by Sale.
After sitting out the remainder of the domestic season, he will link up with England for their summer training camp on 20 June ahead of the August internationals against Wales, home and away, and Ireland.
The incident occurred as Cueto and Day, who are former Sale team-mates, scrapped off the ball in the build-up to the Sharks' second try, scored by Wame Lewaravu.
Television replays showed Cueto's hand bent like a claw as it made contact with Day's face.
"At the hearing Cueto did not contest the citing and he was suspended for nine weeks," the RFU said.
"The suspension runs from 4 April to 6 June and he can resume playing on 7 June.
"The panel decided this was a mid-entry offence, which attracts a ban of 18 weeks, but because of the player's compelling mitigation he received the full 50% discount."
Cueto has scored 16 tries in 50 games for England since making his debut in 2004 and was a key player in their 2011 Six Nations success.
The World Cup begins in New Zealand on 9 September.
Northampton hooker Dylan Hartley missed the 2007 World Cup after he was banned for 26 weeks after being found guilty of a similar offence.
This post was made using the Auto Blogging Software from WebMagnates.org This line will not appear when posts are made after activating the software to full version.