Italy heads to the polls on Sunday 4 March.
Barred from holding office himself, 81-year-old Berlusconi announced Tajani was his preferred candidate earlier this week.
Berlusconi welcomed Tajani's announcement, saying, “I know it's a shame to take Antonio Tajani away from Europe, but it's in the best interest of Italy.”
On Thursday, Tajani tweeted his thanks for the ex-Italian leader’s “gesture of respect”.
Tajani, a Forza Italia co-founder in 1994, wrote, “I told him that I was willing to serve Italy.”
Two other Italian MEPs are standing for a seat in the Senate in the election, including Gianni Pittella, most recently leader of the Socialist group in Parliament.
The other is ENF group Vice-Chair Matteo Salvini.
Friday is the last day of campaigning allowed before the Sunday vote. Berlusconi’s centre-right alliance is predicted to win the most seats but still fall short of a governing majority.
His coalition partners include the anti-migrant League and nationalist Brothers of Italy.
They have agreed that if the bloc wins an absolute majority on Sunday, the party that takes the most votes can pick the next Prime Minister although, ultimately, the decision lies with Italian President Sergio Mattarella.
Polls had showed Forza Italia maintaining a steady lead over the League.
The 64-year-old Tajani, a former journalist, was elected to Parliament in 1994 and has spent most of his political career in Brussels including a stint as a European commissioner.
He served as transport Commissioner in 2008-10 and then as industry Commissioner in 2010-14.
He became Parliament President in January, 2017 when Martin Schulz left the job to return to national German politics.
If successful, it would mean Parliament would have to find another president, just over 12 months before the European elections in 2019.
Schulz, Tajani’s predecessor as president, stood for the chancellorship in Germany after leaving Brussels. After his failure to beat Angela Merkel he recently stood down as leader of the Social Democrats. It is not known if he plans to return to European politics.
Berlusconi has served as Italy’s prime minister four times, but is barred from holding public office until 2019 because of a 2013 tax fraud conviction.
Also standing on Sunday is Maria-Laura Franciosi, a Brussels based former Italian journalist.
She is a candidate of the Partito Democratico for the Italian Senate at the 2018 Italian elections for the European constituency.
Voting in the Europa constituency stopped on Thursday when ballot papers were sent to Rome. Counting will start after the voting in Rome stops at 23h of March 4th
She told this website, “It is difficult to say what will happen. I fear for Italy, let alone my own case. There has been so much hatred in the campaign. It is unbelievable. In the Europe constituency where I have been campaigning it has been much more muted with people asking mainly to count.
“They fear Italy has forgotten all their sacrifices which helped Italy's recovery after the war. This is unfortunately the case. Nobody wants to remember and they now want to throw migrants in Italy out.”
She added, “The risk of riots is high.”
Meanwhile, left-wing MEPs have criticised a Parliament vote which they say will allow serving European commissioners to run for election to Parliament without first having to take an unpaid leave of absence.
At the time of the last European elections in 2014, seven commissioners, including Tajani, ran for the Parliament. Tajani was elected and went on to become a vice president of Parliament before taking on the president’s post.
As well as Tajani, the other European commissioners who stood in the poll were Olli Rehn, Viviane Reding, Maros Sefcovic, Janusz Lewandowski, Neven Mimica and Karel de Gucht.
With the next European elections now less than 18 months away, the issue of allowing commissioners to run for office while on full pay has come under the spotlight.
GUE/NGL group MEPs have expressed concerns about the impartiality and transparency of the electoral process.
German GUE MEP Helmut Scholz has warned of a possible conflict of interest, saying, “The electorate must be allowed to make up their minds independently - based on neutral information.
“That leads to this question: are the Commissioners fulfilling their duties by exercising their authority and resources, or are they actually working on behalf of a political party?”
“To avoid conflicts of interests, the only solution is for commissioners to take unpaid leave and to relinquish their positions. No other solution can be allowed by the European Parliament.”