The suspected attacker was arrested at an address in the east London town on Monday afternoon and remained in custody. He is believed to have been a stranger to Ms Aleena, the force said.
Ms Aleena was a local woman attacked at night walking along Cranbrook Road towards Gants Hill station, police said. She was found by members of the public and police were informed at 2.44am on Sunday.
Paramedics rushed Aleena to hospital where she received treatment but died shortly after.
A post-mortem examination found her death was caused by multiple injuries. No evidence has been found that weapons were used in the fatal attack.
Chief Superintendent Stuart Bell, the senior officer for the Met’s East Area, said: “A full forensic examination of the scene and the surrounding area, house to house enquiries and a focus on identifying all available CCTV has been taking place since yesterday and local people will continue to see a significant police presence over the coming days and weeks.
“Our priorities are to ensure the safety of the local community and to engage locally with residents and people affected.”
Police said they had notified Aleena’s family and were offering support and keeping them updated on the investigation.
Sam Tarry, Labour MP for Ilford South, said the attack on Aleena was “shocking” and would spread fear in the local area.
He added: “My message really to my constituents is that we will do everything to remember this woman who’s lost her life in this horrendous way.
“I think over the next few days we may look at putting on a vigil, something to make sure that, you know, our community all pulls together because people will be very scared.”
A man living nearby the murder scene said the attack made him worry for other local women.
Subhash, 60, said: “It’s not just my daughter, it’s other daughters, other girls, other women in the area.
“It’s quite a serious matter, how safe are you in your own area?”
Ch Supt Bell said police were aware the attack may make local women feel less safe. He said tackling violence against women and girls was a priority for the Met.
“Women should not have to change their behaviour and should be able to go about their business, feeling safe, any time of day or night. It’s our job to ensure that happens – but officers cannot be in all places at all times.
“I would urge our community, especially women, to report any suspicious or unwanted behaviour and seek help if you feel threatened.”
The murder investigation was ongoing and police have asked anyone who was in the area around Cranbrook Road between 2 and 3am on Sunday to get in touch, including any drivers with dashcam footage.
Ch Supt Bell said: “We also want to hear from anyone who saw anything suspicious in the wider Ilford area overnight.
“Anyone with information or footage, or any witnesses, are asked to call the major incident room on 0208 345 3715.”
Police initially said Aleena was aged 36 before issuing a correction.