"The general security situation and the terror threat have an impact on how the police act," police chief Jürgen Mathies told reporters.
He noted that concrete blocks had been installed at the city's famous summer fireworks display, the Kölner Lichter, which took place shortly after a truck attack in Nice during France's July 14th celebrations left 86 dead.
"The events in Berlin have made it clear once again that this is necessary," Mathies said.
Carnival - or Karneval - is the biggest event in the western city's calendar, typically drawing crowds of well over a million. Costumed revellers will take to the streets for parades and shows this year throughout the last week of February, but the high concentration of visitors presents security worries.
As well as concrete blocks, police vehicles will also be placed at strategic points to stop any other large vehicles entering the Carnival area.
Twelve people died in the December attack in Berlin when a truck ploughed through a busy Christmas market. A further 11 of the more than 50 injured were still in intensive care at the start of January, in hospitals around the capital.
German lawyer Andreas Schulz, who represents some of the attack victims and their relatives, warned earlier this month that victims could pursue multi-million-euro compensation claims if it emerged that security measures had been inadequate.
"The question is why the concrete blocks around the market were put up only after the attack and not before," he said, noting that this should have been an "obvious" security consideration after the attack in Nice.
The market at Berlin's Breitscheidplatz, along with others around Germany and in other European cities, installed concrete blocks in the days after the attack - prompting many to ask why this precaution had not been taken sooner.
Last year's Carnival saw a beefed-up police presence in the wake of mass sexual assaults at the city's 2015-16 New Year's Eve celebrations.
Some 2,500 police officers were on patrol - twice as many as in 2015. City authorities spent around €475,000 on personnel costs and new equipment to cover the Carnival weekend.
Closed-circuit television cameras were installed, and bans imposed on known petty thieves, including suspected pickpockets who took part in the crime spree on New Year's Eve. But despite the additional measures, overall attendance was down at the event.
Security at the event last year. Photo: DPA