He also ruled that the principle of natural justice was breached by the Senate's Ethics and Privileges Committee by allowing Senator Dino Melaye, who was the complainant, to participate in the committee's sitting that considered the issue and also allowed him to sign the committee's report.
It said since it is yet to secure a stay of execution order, it could not stop the lawmaker from resuming.
The judge further stated that the court took judicial notice of the fact that while the suit was pending in court, the senate went ahead to suspend the senator for 90 legislative days.
He also ordered that the senator be paid all his allowances and salaries for the period he was illegally suspended.
Omo-Agege was suspended over his comment allegedly tarnishing the image of the senate.More news: Ferrari must not be 'blind' to Spanish GP weaknesses - Sebastian Vettel
"The Senate has been advised that since the motion for stay of execution of the Thursday (May 10, 2018) judgement shall be heard and possibly determined on Wednesday, May 16, 2018, we shall therefore respect the subsisting High Court judgement and await the appellate court's decision on the pending motion". At this time, Omo-Agege was not anywhere around the chamber.
Spokesperson for the Senate, Sabi Abdullahi, said Omo-Agege will be allowed to resume based on advice by lawyers.
Some staff of the assembly, who pleaded anonymity, told NAN that the development was not unconnected with the expected return of Omo-Agege to the chamber on Tuesday after the court judgment in his favour.
His suspension was based on is comment that amendment to section 25 of the Electoral Act, 2010 (as amended), bordering on reordering of elections sequence was targeted at President Muhammadu Buhari.
The Federal High Court in Abuja last week nullified the suspension of Senator Ovie Omo-Agege by the Senate.More news: Nigeria Senate increases 2018 budget estimate
Mr Omo-Agege was also not in his office. Justice Nnamdi Dimgba, in the judgment, said the order nullifying the suspension was "with immediate effect".
Omo-Agege, who represents Delta Central Senatorial District, filed the suit to challenge his suspension from the senate.
According to him, the judgment is binding on the Federal Government, represented by the AGF, and the security agencies under it.
"In particular, the Executive should, as a matter of urgency, purge itself of contempt of court by complying with the judgment of the Federal High Court delivered on December 2, 2016 which directed that Sheik Ibraheem Elzakzaky and his wife, Hajia Zeinab Elzakzaky be released from the illegal custody of the State Security Service".More news: Pakistan top brass blast ex-PM over Mumbai attack remarks